Primary Immunodeficiency Disease: Underdiagnosed at any age

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1 Primary Immunodeficiency Disease: Underdiagnosed at any age
April 25, 2017 Anne L Sherwood, PhD Director of Scientific Affairs The Binding Site, Inc.

2 Learning Objectives Identify the difference between primary and secondary immunodeficiency, and understand categories of Primary Immunodeficiency Diseases (PIDD). Recognize testing methodology for determining presence of a PIDD. Understand potential economic impact of lack of diagnosis of a PIDD. 2

3 What is immuno-deficiency Warning signs Laboratory investigation
Types of PIDD Consequence of delayed diagnosis

4 What is immunodeficiency?
Immune systems ability to fight infectious disease is compromised or entirely absent Immunodeficiency refers to a state in which the immune systems ability to fight infectious disease is compromised or entirely absent. Patients with immunodeficiency often present with infections but these need not be unusual or severe.

5 What is immunodeficiency?
Primary Immunodeficiency disorders can result from a primary congenital defect (PID) or may be acquired from a secondary cause (SID)such as viral or bacterial infection, malnutrition, treatment with drugs that induce immune suppression. Immunodeficiency presenting in adults may be secondary (e.g. HIV, lymphoma, drugs) or primary (usually antibody deficiency). HIV is the most common cause of secondary immunodeficiency – affecting approximately 0.2% of men and 0.1% of women in UK, a quarter of them undiagnosed. Transient immunodeficiency – characterised by recurrent infections and reduced serum immunoglobulins. Patients typically recover at around months of life. Transient Secondary

6 Types of Immunodeficiency
Primary Secondary Born with defect Genetic mutation in an immune system protein Born with normal immune system Caused by other factors Malnutrition Viruses (HIV) Irradiation/chemotherapy Corticosteroids Leukemia Metabolic disease (e.g. diabetes, liver disease) Transient Characterised by: Recurrent infections Reduced serum Igs Patients typically recover at around months of life. Immunodeficiencies can be grouped in two major classes – those that are genetic (Primary) compared to those that are not.

7 What is immunodeficiency?
Primary This talk is concerning PID. Transient Secondary

8 What is primary immune deficiency (PID)?
Over 250 types Genetic defects in ≥1 components of the immune system Incidence 1/1200 Childhood or adulthood Increased infections: Increased rates of malignancies and autoimmunity Serious Persistent Unusual Recurrent Runs in family SPUR Large and growing number of over 250 conditions. Rare and chronic conditions caused when components of the immune system are defective. . Contrary to common perception, PID often presents for the first time in adulthood. Incidence is 1 in While PIDs are generally recognised as rare disorders, some are more common than others. The overall incidence is at 1 in 10,000 (excluding IgA def). Selective IgA deficiency is common (1 in 500 to 1in 700) but most cases individuals are asymptomatic and no not suffer from infections. If not treated , PIDs can be chronic, life-long and even fatal. Due to the defects in their immune systems, people with PID are more prone to infections cause by microorganisms such as bacteria, viruses, fungi and protozoa. SPUR acronym: Immunodeficiency should be considered in patients with severe, persistent, unusual or recurrent infections. In addition a poorly regulated immune system can leave to autoimmunity, leading to inflammation and/or autoimmunity. Chapel et al. 2014 “The primary immunodeficiency community often identifies with zebras. This is based on an old saying. In medical school, many doctors learn the saying, “when you hear hoof beats, think horses, not zebras” and are taught to focus on the likeliest possibilities when making a diagnosis, not the unusual ones. However, sometimes physicians need to look for a zebra. Patients with PI are the zebras of the medical world. So IDF says THINK ZEBRA!”

9 First recorded history of PIDD – 1952 by Col. Ogden Bruton
8 year old boy with recurrent Pneumococcal sepsis ≥ 19 episodes in 4 years No gamma globulins by SPE Vaccination – no effect Transferred IgG antibodies - levels lasted for six weeks. Monthly intervals of Ig therapy – free from infection (1st recorded case of Ig replacement therapy for PID) Later identified as Bruton-type or X-linked agammoglobinemia (XLA) Mutation in Btk gene Bruton 1952 Pediatrics 9:

10 How common is PID? Adult Onset
However, a national survey of PID done in 1995 in the United States found that more than 40% of patients with these disorders were not diagnosed until adulthood (Figure 1A), despite the fact that many reported serious or chronic health conditions prior to diagnosis, such as sinusitis, bronchitis, and pneumonia (see Figure 1B) [11].

11 Warning signs of immunodeficiency
These warning signs were developed by the Jeffrey Modell Foundation Medical Advisory Board. Consultation with Primary Immunodeficiency experts is strongly suggested. ©2013 Jeffrey Modell Foundation Immunodeficiency should be considered in patients with severe, persistent, unusual or recurrent infections. Often diagnosed after “too many infections”. This presents a significant challenge to the clinician because infections are so common in normal subjects (frequent 6-11 upper respiratory infections are common per year in young children, especially is exposure to older siblings, day care centres or coexisting respiratory allergies). When frequent and prolonged infection are coupled with failure to thrive or other of these indications ID should be considered. Jeffrey Modell foundation have developed ten warning signs of PID. It is recommended that all patients affected with 2 or more of these warning signs be screened for an underlying PID. Contrary to common perception, PID often presents for the first time in adulthood. There are several diagnostic protocols which have been developed to enable doctors to recognise the symptoms and signs of PID, these will be covered in a subsequent talk. N.B. Family history: some of these disorders are inherited as either X-linked or autosomal-recessive inherited traits. A history of consanguinity should be sought, important clues in other family members include foetal death, autoimmune disorders and lymphoreticular malignancies. Failure to thrive: often in infants and children, but its absence does not exclude an immunodeficiency. In adults, weight loss or loss of subcutaneous fat is a more common manifestation.

12 PID is not just a disease of children

13 Severe Combined Immune Deficiency
Most severe form of PID 1:100,000 births X-SCID, most common SCID (♂) Impaired development of T cells B cells present but non functional (no antibody) Recurrent infections develop in children <6 months. Failure to thrive Considered a “Pediatric Emergency” States screening all newborns for SCID are: WI, MA, NY, CA, CT, MI, CO, MS, DE, FL, TX, MN, IA, PA, UT, OH, WY and KS. Considered a “Pediatric emergency”: States screening all newborns for SCID are: WI, MA, NY, CA, CT, MI, CO, MS, DE, FL, TX, MN, IA, PA, UT, OH, WY and KS. (18)

14 Severe Combined Immune Deficiency
David Vetter ( ) Lack of T cell function Impaired B cell formation SCID: Predisposed to severe and rare infections. Incidence 1:50,000. Lack of T cell function and impaired B cell formation. Severe symptoms within 3-6 months of birth. Death within 12 months if not treated correctly. Stem cell transplant/gene therapy required. “Pediatric emergency”. New born screening is now available (US), Not included in New Born Screening in all countries, not yet in UK.

15 David Vetter, the Bubble Boy
b1971 with SCID at Texas Children’s Hospital in Houston Infant older brother died of same thing so germ-free delivery arranged Lived in sterile plastic bubble until age 12 Given imperfect match bone marrow transfusion at 12 from sister- became sick Lived for 15d out of bubble to get treatment – died from Burkitt’s lymphoma (latent EBV) in 1984, 4 mos after transfusion. Genetic defect in his cells that caused SCID was identified (Noguchi 1993 Cell) 8/9 children that received gene therapy for X-SCID (IL2R common ᵞ chain receptor) are alive & living ‘outside’ (Dr. David Williams, Boston Childrens Hospital, ASH 2013).

16 Another notable: First Gene Therapy Recipient – Ashanthi DeSilva
Born with ADA-SCID, adenosine deaminase def. At age 4, 9/14/90, her IV treatment at NIH marked first authorized test of gene therapy on a person in US. Dr. W. French Anderson, Dr. Michael Blaese, and Dr. Kenneth Culver performed historic & controversial experiment. Her T cell counts returned to normal within 6 mos. Treated cells did produce ADA, but did not grow. Consequence afterwards she had repeated gene therapy treatments & enzyme replacement (PEG-ADA) therapy. But considered a success.

17 Case study: Patient P Is this normal? At birth
Weight 3.1 kg (~25th centile) 3 months Otitis media Upper respiratory tract infection 5 months Haemophilus influenzae pneumonia 11 months 16 months Balanitis At birth Weight 3.1 kg (~25th centile) 3 months Otitis media Upper respiratory tract infection 5 months Haemophilus influenzae pneumonia 11 months 16 months Balanitis 18 months Pale and thin Weight below 3rd centile No family history Case 3.1 X-linked agammaglobulinaemia (Bruton's disease) Peter was born after an uneventful pregnancy and weighed 3.1kg. At 3 months, he developed otitis media and an upper respiratory tract infection. At the ages of 5 months and 11 months, he was admitted to hospital with Haemophilus influenzae pneumonia. The infections responded promptly to the appropriate antibiotics on each occasion. When 16 months old, he developed balanitis. He is the fourth child of unrelated parents: his three sisters show no predisposition to infection. Examination at the age of 18 months showed a pale, thin child whose height and weight were below the third centile. There were no other abnormal features. He had been fully immunized as an infant (at 2, 3 and 4 months) with tetanus and diphtheria toxoids, whole-cell pertussis, Haemophilus conjugate vaccine and oral polio. In addition he had received measles, mumps and rubella vaccine at 12 months. All immunizations were uneventful. Immunological investigations (Table C3.1) into the cause of his recurrent infections showed severe panhypogammaglobulinaemia with absent antibody production. Although there was no family history of hypogammaglobulinaemia, the absence of mature B lymphocytes in his peripheral blood strongly supported a diagnosis of infantile X-linked agammaglobulinaemia (Bruton's disease). His antibody deficiency was treated by 2-weekly intravenous infusions of human normal IgG in a dose of 400mg/kg body weight/month. Over the following 2 years, his health steadily improved: his weight and height are now on the 10th centile, and he has had only one episode of otitis media in the last 18 months. Is this normal?

18 Warning signs of immunodeficiency
Patient shown to have 2 of the warning signs from the Jeffery Modell Foundation. These warning signs were developed by the Jeffrey Modell Foundation Medical Advisory Board. Consultation with Primary Immunodeficiency experts is strongly suggested. ©2013 Jeffrey Modell Foundation

19 X-linked agammaglobulinaemia (XLA)
Case study: Patient P Serum immunoglobulins Normal range IgG (g/L) 0.17 5.5 – 10.0 IgA (g/L) Not detected 0.3 – 0.8 IgM (g/L) 0.07 0.4 – 1.8 Anti-Tetanus toxoid IgG Not detectable Anti-Diphtheria toxoid IgG Serum immunoglobulins Normal range IgG (g/L) 0.17 5.5 – 10.0 IgA (g/L) Not detected 0.3 – 0.8 IgM (g/L) 0.07 0.4 – 1.8 Anti-Tetanus toxoid IgG Not detectable Anti-Diphtheria toxoid IgG Blood lymphocyte subpopulations (x109/L) Total lymphocyte count 3.5 2.5 – 5.0 T cells (CD3) 3.02 1.5 – 3.0 B cells (CD23) <0.03 0.1 – 0.4             (CD19) <0.1 0.3 – 1.0 (CD20) NB Normal ranges for age 18 months Immunological investigations into the cause of his recurrent infections showed severe panhypogammaglobulinaemia with absent antibody production. Although there was no family history of hypogammaglobulinaemia, the absence of mature B lymphocytes in his peripheral blood strongly supported a diagnosis of infantile X-linked agammaglobulinaemia (Bruton's disease). X-linked agammaglobulinaemia (XLA)

20 X-linked agammaglobulinaemia (XLA)
Case study: Patient P Immuno-deficiency Primary BTK gene X Y X-linked agammaglobulinaemia (XLA) Further investigations would have shown a mutation in the BTK gene (Bruton’s tyrosine kinase) which is located on the long arm of chromosome X (Xp21.3 – Xp22). This gene has 19 exons and to date 544 mutations have been characterised. XLA is a monogenetic disease. Transient Secondary

21 X-linked agammaglobulinaemia (XLA)
Early pro-B cell Late pro-B cell Large pre-B cell Small pre-B cell Stem cell Btk Heavy chain Light chain Surrogate light chain So lets have a quick look at how alterations in the BTK gene can cause the phenotypic characteristics of X-linked agammaglobulinemia as seen in this patient. Basic defect in XLA is an inability to produce antibodies. Antibodies are produced by specialised cells called plasma cells. Plasma cells develop in an orderly sequence of events beginning with stem cells in the bone marrow. The stem cell gives rise to immature lymphocytes called early pro-B cells, which develop into pre-B cells, which give rise to immature B cells. The immature B cells express the B cell receptor which is a surface immunoglobulin able to bind to antigens and be triggered to differentiate into plasma cells secreting antibodies. The differentiation of precursor cells into immature B lymphocytes then into plasma cells is a process regulated by the products of many genes. It involves the rearrangement and expression of the heavy and light chains of the B-cell receptor. BTK is involved in the process of Light chain rearrangements. In XLA cell maturations stops after initial heavy chain gene rearrangement because of the mutation in the tyrosine kinase. Patients with XLA have normal amounts of pro-B cells but few Immature B cells in circulation. Immature B cell B-cell receptor

22 X-linked agammaglobulinaemia (XLA)
Early pro-B cell Late pro-B cell Large pre-B cell Small pre-B cell Stem cell Btk Heavy chain Light chain Surrogate light chain In XLA cell maturations stops after initial heavy chain gene rearrangement because of the mutation in the tyrosine kinase. Patients with XLA have normal amounts of pro-B cells but few Immature B cells in circulation. Immature B cell B-cell receptor

23 Case study: Patient P Treatment
2-weekly intravenous infusions of human normal IgG (IvIg). His antibody deficiency was treated by 2-weekly intravenous infusions of human normal IgG in a dose of 400mg/kg body weight/month. Over the following 2 years, his health steadily improved: his weight and height are now on the 10th centile, and he has had only one episode of otitis media in the last 18 months. 4 years Weight now on the 10th centile Only one episode of otitis media in the past 18 months

24 Types of primary immunodeficiency (PIDD)
(PAD) There are over 230 different inherited rare disorders caused by mutations in genes encoding proteins involved in the immune system PID are usually classified into major groups according to the predominant immune mechanism that is defective/interrupted. There is some overlap, e.g. SCID is severe combined immunodeficiency – T-cell and B-cell defects This chart shows main diagnostic categories of (PID) patients entered in the ESID (European Society for Immunodeficiencies) Registry as of Nov. 15th, The ESID Registry is the largest registry worldwide with 19,366 patients (both children and adults) Around 57% of PID patients are those with antibody disorders. Main take home message is that antibody deficiencies are the most common PID – accounting for 50-65% of PIDs. Additional background information for presenters: In agammaglobulinemia, the most severe form of antibody deficiency, patients almost completely lack immunoglobulin (Ig) from the second half of the first year of life (during the first months of life transplacentally transferred maternal IgG is present). In many cases but not all this is due to an X-linked gene defect leading to a maturation arrest in B-lymphocyte development in the bone marrow. Cellular (T-cell) disorders account for 5-10% if PIDs. Phagocytic deficiencies (granulocytes and monocytes) constitute 10-15% PIDs. Defects of neutrophil and monocyte maturation and differentiation, chemotaxis, phagocytosis and intracellular killing have been described. Complement deficiency can result in inadequate coating of bacteria with antibody (opsonization), reduced or absent phagocytosis or lysis of microorganisms. These defects can lead to severe sepsis. The most common complement defect is C1 inhibitor deficiency, which results in attacks of swelling. Complement disorders account for a small percentage of PIDs (<2%) and may coexist with autoimmune diseases such as systemic lupus erythematosus. 56.7% Adapted from Mahlaoui, Rare Diseases and Orphan Drugs 2014;1:25-7

25 Review: Structure & Function of Antibodies
Allergy. Binds to allergens and triggers histamine release. Also anti-parasitic. Long-term secondary immunity. Most common. Provides majority of Ab-based immunity against pathogens. Memory Abs. Only Ab capable of crossing placenta. Antigen receptor on B cells that have not been exposed to antigens. Activates basophils and mast cells. 1% 0.002% 75-80% 10-15% Secretory. Found in mucosal areas (gut, respiratory tract) to prevent colonization by pathogens. Also found in saliva, tears, and breast milk. 5-10% 5 classes of Antibodies. Start with Ig E, IgD, IgA, Ig M and finish with IgG. . IgG most prevalent. Involved in secondary immunity. There are 4 subclasses of IgG. Primary. Eliminates pathogens in early humoral response (before there is enough IgG). On surface of B cells.

26 Tests to investigate Immunodeficiency
IgG, IgA, IgM IgG subclasses Specific antibodies Complement Lymphocyte/Phagocyte count & function SPE and sFLC The tests used when investigating a patient for immunodeficiency are clinician dependent, usually starting with basic screening tests and further complex tests are performed when indicated. This chart shows assays commonly be used to investigate immunodeficiency (NB TBS produces most of these assays but TBS does not produce test to determine lymphocyte and phagocyte function) Additional information for presenter: Full blood count – These tests are of great clinical importance because they allow the physician to know whether the lymphocyte, neutrophil and platelet counts are normal. This is often a first stage screening requested before more specialised tests are performed (as seen in chart on slide). Serum immunoglobulins – because antibody defects are more common than any other immune defect, the first emphasis should be places on investigation of serum immunoglobulins and antibody production. Because immunoglobulin values increase with age, comparison to age-matched controls is necessary for correct interpretation. IgG subclasses can be determined, but there interpretation is more difficult. IgG1 accounts for 60-70% of total IgG, therefore most cases of IgG1 deficiency will be apparent as hypogammaglobulinaemia without the need to test for IgGSC’s. However, substantial deficiencies of IgG2, IgG3 and IgG4 may exist with normal IgG levels. Important anti-polysaccharide antibodies are often located in the IgG2 subclass (de Vries, 2008). Specific antibodies - It is important to determine if antibodies which are being produced are functionally relevant. This can be performed by using vaccination as a diagnostic test for specific antibody formation. These tests are of crucial importance in determining whether there is truly an antibody deficiency disorder when the serum immunoglobulins are not very low or even if they are low. It is important to test for antibodies to both protein (i.e. tetanus or diphtheria) and polysaccharide (i.e. pneumococcal polysaccharides) antigens. Isohemagglutinins (antibodies to red blood cells) are natural anti-polysaccharide antibodies; if they are missing this also suggests an antibody deficiency disorder. Complement - Evaluation of the complement system is appropriate for patients with episodes of bacteraemia, meningitis or systemic Neisserial (either N. meningitidis or N. gonorrhea) infections. CH50 is an excellent screening test, Alternative Pathway defects can be screened for with the AH50 test. Lymphocyte/phagocyte count and function - Analysis of lymphocyte surface markers, using monoclonal antibodies and flow, can identify T and B cells, subpopulations of T cells and NK cells and monocytes and macrophages. SPE and sFLC to assess for presence of M proteins to rule out lymphoproliferative disease. Laboratory evidence of immunodeficiency may be identified indirectly during the course of routine testing for vague clinical presentations. When the investigation of immunodeficiency is being considered, discussion of appropriate microbial investigation should take place. Specialised culture or molecular tests for a wider range of organisms may be identified. HIV tests are also often required to rule out SID. More advanced laboratory studies may also be ordered, e.g. measurement of adenosine deaminase in SCID, genetic studies. Often performed in a research setting. de Vries, Clin Exp Immunol 2012;167:108-19

27 Total Immunoglobulins (Ig)
Why test ? Dysgammaglobulinemia is a major hallmark of a PAD Levels of IgG, IgA, IgM and IgD Compare to age specific normal ranges Diseases Specific Disease Gene Defect Ig Status Absent B cells XLA BTK  IgG, IgA, IgM and IgD Normal/Low B cells CVID e.g. TACI deficiency TACI  IgG, IgA but IgM variable CSR deficiencies (normal/high B cells) e.g. Uracil-DNA Glycosylase deficiency UNG IgG, IgA but IgM normal or elevated (Class switching requires recombination) Selective IgA deficiency Unknown  IgA but IgG and IgM normal SAD with normal Igs (normal B cells) IgG, IgA, IgM all normal IgG Sc normal Periodic Fever Syndromes MVK IgG and IgM can be normal IgD may be elevated Selective IgA deficiency is one of the most common PIDs. Studies have indicated 1:500 caucasions have it. Many have relatively mild illnesses and may never discover IgA deficiency. CSR: Class switch recombination deficiency SAD: Specific antibody deficiency CVID common variable immunodeficiency, found in about 1 in 25,000 persons;

28 Properties of IgG Subclasses
Why test IgG subclasses? PAD may occur even with normal IgG level 4 subclasses of IgG with different serum range IgG1 IgG2 IgG3 IgG4 Adult Serum Range (g/L) 4.9 – 11.4 1.5 – 6.4 0.20 – 1.10 0.08 – 1.40 % Total IgG 43-75 16-48 1.7 – 7.5 0.8 – 11.7 Half-life (days) 21 7 Ab response to: proteins ++ +/- polysaccharides + - allergens Complement activation: +++ IgG subclass deficiency - maybe asymptomatic or recurrent infections - may have poor response to specific antigens The IgG class of antibodies can be subdivided into 4 different subclasses IgG1, 2, 3 and 4. As you can see from this table, IgG1 and 2 are the most abundant in the serum. IgG2 is usually assocciated with immune response to polysaccharides, while IgG1 and 3 are more associated with immune responses to proteins (from the bacteria, virus or immunogen).. Remember IgG1/3 involved with protein response. IgG2 with carbohydrate. IgA1: protein, IgA2, polysacchride bacteria

29 Vaccine Response assays and response to normally encountered pathogens
Why test ? Measure ability of immune system to produce functionally active specific antibodies towards specific vaccines. Deficiencies can occur with normal IgG and IgG subclass levels. e.g. Specific Antibody Deficiency (SAD). Examine T-cell dependent and T-cell independent responses Poor response indicates immunodeficiency Polysaccharide (carb) Protein-Polysaccharide conjugate Protein Tetanus toxoid Diphtheria toxoid Varicella Zoster Virus (glycoprotein) Hib Haemophilus influenzae type b (behaves like a protein antigen) PCP Pneumococcal capsular polysaccharide Typhi Vi Salmonella typhi vi Tests should include responses to: Remember IgG1/3 involved with protein response. IgG2 with carbohydrate. IgA1: protein, IgA2, polysacchride bacteria

30 Types of antibody deficiency
Common Variable Immune Deficiency Low/absent IgG & Low/absent IgA Low/normal IgM Poor response to vaccines >4 years of age (20-40 years) IgA Deficiency Low serum IgA Normal serum IgG and IgM Normal IgG Ab response to vaccines >4 years of age CVID: 1 in 25,000 Caucasians . Characterised by progressive late onset hypogammaglobulinemia, can become apparent in childhood or adult life. The hallmark is reduced serum immune globulins. IgG, IgA and/or IgM >2SD below the mean. Usually IgG is <400mg/dL (normal range mg/dL). Antibody production (i.e. response to vaccines) is absent or reduced. Most cases T and B cell numbers are normal. The average age of diagnosis is years. Pathogenesis poorly understood. Family members commonly normal, suggesting complex inheritance and or environmental factors. Treatment is IVIg and antibiotics. Selective IgA deficiency: This is the most common antibody deficiency. Common defect, incidence 1:500 Serum IgA (<5mg/dL) with normal IgG and IgM. In 12% cases it is associated with selective IgG2 deficiency. Most people with IgA deficiency are asymptomatic (increased incidence of asthma, autoimmunity, celiac disease). Relevence of IgA deficiency is hard to interpret as the clinical phenotype can range from perfect health to recurrent pneumonias with bronchiestasis.

31 Types of antibody deficiency
IgG Subclass Deficiency Normal levels of IgG, IgA and IgM Two of IgG1-3 subclasses low or deficient Poor response to some vaccines Specific Antibody Deficiency Normal levels of IgG, IgM and IgA Normal IgG subclass levels Poor response to most polysaccharide vaccines IgG subclass deficiency: The clinical relevance of IgGScD is a matter of debate. IgG1 accounts for 60-70% of total IgG, most cases of IgG1 will become apparent as hypogammaglobulinemia without testing for IgGSc deficiency. However, substantial deficiencies of IgG2, IgG3 may exist with normal levels of IgG. Specific Antibody deficiency: SAD there is a significant functional antibody deficiency even in the presence of normal serum immunoglobulin levels.

32 Types of antibody deficiency
Laboratory investigations IgG IgG subclass IgA IgM Vaccination response CVID Low Abnormal Normal/ low Poor IgA deficiency Normal Absent deficiency Two of IgG1/ G2/G3 low May be poor Specific antibody deficiency (mostly polysaccharide) Summary of the previous two slides. This table shows laboratory findings (total immunoglobulin / IgGSc / Vaccine response) in CVID/IgAD/IgGScD/SAD.

33 Treatment Stem cell transplant Antibiotics IVIG
The most satisfactory treatments of PID could be achieved by the use of immunoglobulin replacement, antibiotics, immunosuppressant and hematopoietic stem cell transplantation.

34 Case Study 1 IgA and IgG SUBCLASS DEFICIENCIES
48 year-old man – admitted for weight loss associated with intermittent diarrhea History of pneumonia as a child and once as a young man At age 33 years – chronic sinusitis, persistent headaches, under-weight Investigations 1. Total serum IgG and IgM – normal but IgA - very low. 2. IgG1/3 – very low IgG2 – normal IgG4 – high 3. Immunization responses – T.tox, Diphtheria – poor response, Pneumovax – normal response Diagnosis Remember Tet tox, Dip are proteins, IgG1/3 involved with proteins. Pneumovax is polysacchride, IgG2 IgA and IgG SUBCLASS DEFICIENCIES (with chronic sinusitis) Essentials of Clinical Immunology. H. Chapel et al.

35 Case Study 2 Diagnosis IgG SUBCLASS DEFICIENCY 35 year old woman
History of recurrent respiratory tract infections, candidiasis and urinary tract infections No underlying cause – symptoms possible pychosomatic! Treated for depression Investigations (Referred to hospital immunology department) 1. Total serum IgG, IgM and IgA normal 2. IgG1 – normal IgG2 – normal IgG4 – normal 3. IgG3 – greatly reduced Diagnosis IgG SUBCLASS DEFICIENCY (recurrent infections reduced with subsequent IVIG therapy) Snowden, et al 1984

36 Case Study 3 3 mos old - developed otitis media and an upper respiratory tract infection 5 mos and 11 months – Haemophilus influenzae pneumonia 16 mos – Candida infection 18 mos – failure to thrive Fully immunized – tetanus/diphtheria toxoids, pneumococcal, pertussis, Hib vaccine and oral polio Immunological investigations 1. Total serum IgG/A/M – very low IgG and IgM, no detectable IgA 2. Immunization responses – no IgG antibodies detected Diagnosis Remember Tet tox, Dip are proteins, IgG1/3 involved with proteins. Pneumovax is polysacchride, IgG2 X-LINKED AGAMMAGLOBULINAEMIA (XLA) (confirmed by detection of mutated Btk gene) Essentials of Clinical Immunology. H. Chapel et al.

37 Antibody deficiency and diagnostic delay
Median delay 2 years Major infection Minor infection Hospital stay? Yes No Score 10 points 5 points Examples Pneumonia Meningitis Osteomyelitis Septic arthritis Septicaemia Chest infection (requiring antibiotics) Sinusitis Otitis Gastroenteritis Skin sepsis Accumulated morbidity points There is a often a significant delay in the diagnosis of immunodeficiency. In primary immunodeficiency, delays of over seven years between first presentation and final diagnosis are common. Patients are often reviewed by several physicians without the diagnosis having been considered. Delays in diagnosis and treatment are associated with poor outcomes. PID widely under-diagnosed in most countries Average delay of diagnosis ~ 5 years. Mostly diagnosed after >3 hospital visits Organ damage is possible if PID is not diagnosed early enough. Most common treatment for symptoms is antibiotics. Study Seymour (2005): A retrospective case note review was performed of 89 consecutive patients with antibody deficiency referred to a regional referral centre for clinical immunology in north west England and north Wales. The delay in diagnosis and the estimated resulting morbidity in terms of infections were assessed. A points scheme was designed according to whether the patient had major or minor infections, scoring 10 and 5 points, respectively. Results: Fifty six of the 89 patients experienced delay in diagnosis. The overall median delay was 2 years (mean, 4.4), resulting in substantial morbidity For one patient the morbidity score reached 250 points before a diagnosis was reached. Seymour J Clin Pathol 2005;58:546–547

38 Complement Deficiencies
Rare – only 2% of all PIDs Deficiency of any component of complement cascade (or regulatory proteins) Clinical indications: recurrent mild or serious bacterial infections, autoimmune disease or episodes of angioedema Two categories: Disorders of proteins that inhibit complement system  Overactive immune response Hereditary angioedema and hemolytic-uremic syndrome Disorders of proteins that activate complement system  Underactive immune response Susceptibility to infections No supplemental therapy available

39 Complement Deficiency
Why test ? (1) Even with normal IgG and normal vaccine responses the patient may present with symptoms of PID. (2) Some specific clinical presentations raise the possibility of complement deficiency. Includes: >1 episode of invasive meningococcal infection or other Neisserial bacteria. Guidelines – if all antibody responses are normal and patient has recurrent meningococcal disease test for complement deficiency

40 Serum Proteins in the Complement Pathway
Serum proteins (C1-C9) Lysis of foreign cells (C5-C9 form Membrane Attack Complex MAC) Inflammation (C5a, C3a) via release of histamine, which increases vascular permeability Phagocytosis (C3b) via opsonization MAC complex formation (CH50) Start with some background on Complement and pathway. Note it is Protein-based system (more than 30), not a cell-based system. You are not looking for reduced number of immune cells or dysfunctional cells, but a problem with a missing protein. As a cascade it must follow a certain order of events!!

41 Three mechanisms of complement activation
“starting the complement cascade” Classical Pathway: Initiated by Antibody-Antigen complexes Alternative Pathway: Initiated by microbial polysaccharides. Lectin Pathway: Initiated by lectin binding to mannose on pathogen

42 Activation of Complement Pathway
Innate Adaptive Microbial polysacchrides All 3 pathways converge 3 pathways of complement activation. All converge on C3, to ultimately form membrane attack complex. Lead to formation of MAC

43 Complement Function I: Activation of the Membrane Attack Complex
Here’s an example of the classical complement pathway, which is activated by antibodies bound to a bacteria. This is detected/bound by the C1q-r-s proteins which activate C4 and C2. This cascade eventually leads to formation of the membrane attack complex (C5, C6, C7, C8, C9), which inserts a pore in the bacterial cell membrane and causes lysis/death of the bacteria. MAC: hole punched in bacterial cell membrane

44 Complement Function II: Opsonization
One other function of complement is to bind to bacteria to make them easier to take up by monocytes and macrophages (phagocytosis). This is called opsonization. This is part of the innate immune response (alternative response). Opsonization of pathogens by complement facilitates their uptake by phagocytic antigen-presenting cells that express complement receptors; this enhances the presentation of pathogen antigens to T cells (adaptive)

45 Activation of Complement Pathway
If one of the complement factors (C1 – C9) is missing or dysfunctional, the cascade slows down or stops. 3 pathways of complement activation. All converge on C3, to ultimately form membrane attack complex. TBS assays: Classical: CH50 assay, C2*, C1 inactivator*, Alternative: Individual: C2*, C4, C3c (C3 convertase), * In development The main tests that measure total complement activity are CH50 and CH100.

46 CH50 Clinical Significance
Low CH50 levels suggest possibility of complement component deficiency (C3, C4, C1, etc.) National (IDF) and International (ESID) Guidelines for Primary Immunodeficiency recommend screening with CH50 in diagnostic workup of complement deficiency1,2 Immune Deficiency Foundation (IDF) Diagnostic Care and Clinical Care Guidelines, 2008 2. European Society for Immunodeficiencies (ESID)

47 Assays that Measure Complement
Classical Complement CH50 Screening test – measures total classical complement activity via MAC Complex Formation Recommended as part of diagnostic protocol for Primary Immunodeficiency. Total Hemolytic Complement Kit Detects deficiencies of Classical Complement Pathway and terminal sequence (C3-C9) components Alternative Pathway Hemolytic Complement kit Designed to measure activity of Alternative Complement Pathway (AR50 or AR100) Individual Complement Components Reminder it is Protein-based system, not a cell-based system. You are not looking for reduced number of immune cells or dysfunctional cells, but a problem with a complement protein and pathway. TBS assays: Classical Complement: CH50 assay, C2*, C1 inactivator*, Alternative: Individual: C2*, C4, C3c (C3 convertase), * In development

48 Diagnosis of Complement Deficiencies
Complement Component or Inhibitor defects Ear infections, Pneumonia, Bacteremia, Meningitis, System Neisserial infection Angioadema, laryngeal edema, abdominal pain Laboratory tests Laboratory tests Complement Screening assays: CH50, AH50 Specific assays: Complement components (C1, C2, C3, C4, etc) C1 Esterase Inhibitor Example of an algorithm of Complement testing based on clinical presentation. TBS assays: Classical: CH50 assay, C2*, C1 inactivator*, Alternative: Individual: C2*, C4, C3c (C3 convertase) If abnormal, refer to immunologist for further evaluation, diagnosis and treatment

49 Case Study 4 Diagnosis COMPLEMENT DEFICIENCY (C6 deficiency)
26 yr old male. Extreme headache, vomiting. Lumbar puncture: N. meningitidis cultured from CSF. Immediate family no history of PID Investigations Total serum IgG, IgA, IgM all normal. Immunization responses to T.tox, Diphtheria and Pneumovax all normal. Detectable responses to varicella zoster CH50 no detectable activity. Diagnosis COMPLEMENT DEFICIENCY (C6 deficiency) Essentials of Clinical Immunology. H. Chapel et al.

50 Case Study 5 (C9 deficiency) Diagnosis COMPLEMENT DEFICIENCY
56 year old male previous history of meningitis (purulent meningitis at age 23) Presented with acute meningococcal meningitis (recurrent) Investigations Full lymphocyte count - normal Antibody and subclass levels - normal CH50 and APH50 assays reduced C9 completely absent Diagnosis COMPLEMENT DEFICIENCY (C9 deficiency) Zoppi, et al, 1990 Archives Int Med

51 Review of the Problem PIDs are under diagnosed
Diagnosis is delayed by average of 5 years Impact to health and healthcare resources to underdiagnose Frequent doctor/hospital visits, intensive care Long term morbidity Months off work/school Impact on healthcare resources Economic impact We have covered different types of PIDs and how labs test for them. Let’s review the original problem we mentioned and why awareness is important.

52 Improvement after Diagnosis of PID
Comparing quality of life data per year for undiagnosed vs. diagnosed patients with PID Modell et al, Immunol Res :61-70 Per year

53 Yearly cost of Undiagnosed PID
Modell et al, Immunol Res :61-70

54 Overall Economic impact
Undiagnosed PID patient = ~$102,736/year Diagnosed PID patient = ~$22,794/year Savings by diagnosing PID = $79,942/year According to NIH and phone survey, 150, ,000 cases of PID undiagnosed in the US. Economic impact of undiagnosed PID patients to healthcare system in US could total over $40 billion annually Modell & Modell 2007, Boyle 2007

55 Conclusion Primary Immunodeficiency Disease occurs in both children and adults Lack of awareness and education – widely underdiagnosed conditions Many tests aid the diagnosis of a number of PIDS Immunoglobulins Ig subclasses Levels of Igs that recognize specific antigens after vaccination Classical complement pathway Alternative complement pathway Individual complement components New products may make this process easier for clinician and provide prognostic information to determine patient management. Antibody deficiency Complement deficiency

56 Summary Immunodeficiency – immune systems ability to fight infectious disease is compromised Warning signs can help to identify PID 55-60% of PIDs are antibody deficiencies Laboratory investigations include; Immunoglobulins, IgG subclass, vaccine response Summary: Immunodeficiency is where an individuals immune systems ability to fight infectious disease is compromised. There are warning signs which help clinicians to identify patients who may have a PID 55-60% of patients with PID have antibody deficiencies TBS sell assays used to diagnose PID including total immunoglobulins, IgGSc disease and vaccine response. Delays in diagnosis of PID lead to delayed treatment which is associated with increased morbidity. This can also have cost implications for the healthcare provider. Delays in diagnosis are associated with increased morbidity

57 Resources for Immunodeficiencies
International Union of Immunological Sciences (IUIS) Primary Immunodeficiency Expert Committee European Society for Immunodeficiencies ( Immune Deficiency Foundation ( Jeffrey Model Foundation ( Several major groups promote research and education in immune deficiencies: IUIS – PID Expert Committee - International group of experts assembled by WHO Publishes classifications and suggested guidelines for diagnosis ( They work together with ESID who also publishes guidelines IDF here in the USA And Jeffrey Model Foundation All of these organizations contribute to raising awareness, education, research for immunodeficiency EXTRA INFO The Primary Immunodeficiency Expert Committee was originally set up under the auspices of the World Health Organisation in 1973, to describe and classify the types of primary immune defects affecting humans. The classification of those diseases recognised at the time was published in a report (Cooper MD et al NEJM ) and revised every two years subsequently. However in the 1990s the WHO made a policy decision to concentrate on more common diseases, so the IUIS agreed to take on the remit of this committee; this was formalised at the 54th IUIS Council meeting in Tapei in 2008. MISSION STATEMENT To provide an up-to-date classification of all primary immunodeficiency diseases (PIDs) To assist with the identification, diagnosis and management of patients with these uncommon conditions To support diagnostic and therapeutic guidelines developed by national societies and others, to assist healthcare providers To promote awareness, diagnosis and treatment of PIDs in all regions of the world To produce ad hoc reports on any aspect of PIDs, to assist in the welfare of patients with these conditions

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