Primary Immunodeficiency

1. Primary Immunodeficiency Conleth Feighery Dept. of Immunology MSc in Molecular Medicine 2009

2. Primary Immunodeficiency • Great advances in genetic identification in late 1980s, early 1990s • Over 150 genetic disorders now recognised • Selection of disorders presented here

3. Learning objectives  Primary immuno-deficiency – rare genetic disorders  Secondary immuno-deficiency – common quantitative, disorders  How to suspect its presence, importance of early diagnosis  Tests employed in diagnosis • Implications of immuno-deficiency: infection, malignancy, auto-immunity • Specific treatment of immuno-deficiency states.

4. Secondary immunodeficiency • Multiple factors can affect immune function • Age - reduced function in young, old • Nutrition - dietary defects eg. iron deficient • Developing world - malnutrition • Other disease - eg. cancer • Therapy - drugs, radiation • Viruses - HIV, others

5. Primary Immunodeficiency - examples • Failure of antibody production – cause: btk defect • Failure of T cell:APC interaction – cause: CD40 ligand defect • Failure of T cell development – cause: IL-7 receptor gamma chain defect • Failure of neutrophil killing – cause: NADPH oxidase defect

6. Primary Immunodeficiency • Issues • Delayed diagnosis • Rare genetic defect - diagnosis requires detailed molecular investigation • Patients may have features of rare syndrome

7. Type of infection helps predict the type of immunodeficency • B lymphocyte - pyogenic bacteria - lungs • T lymphocyte - viruses, fungi, mycobacteria • Complement - meningococcus - CNS • Phagocyte - staphylococcus - skin

8. Primary immuno-deficiency Case histories

9. Immunodeficiency - case history. • BB - 25 year old male – unwell as child • Lobar pneumonia x 3 • Family history - 2 brothers died following recurrent lung infections • Investigations - absence of antibodies - IgG, IgA, IgM • DIAGNOSIS - X-linked agammaglobulinaemia

10. BB - patient with XLA

11. Essential role of BTK

12. XLA - BTK defect • Defect in B cell maturation • Genetic disorder - gene on X-chromosome • codes for Bruton’s tyrosine kinase - BTK essential for B cell development

13. Common variable immunodeficiency - case • AB - 29 year old male • Recurrent ear and sinus infections • Strep. pneumoniae lung infection • Malabsorbtion - Giardiasis lamblia infection • DIAGNOSIS - Common Variable Immunodeficiency - CVID

14. Antibody deficiency – infection sites Otitis media Pneumonia - affecting right lower lobe

15. CT scan of lung - bronchiectasis

16. Antibody deficiency 2. • Common variable immunodeficiency - CVID • Incidence - 1:20,000 • Heterogeneous - group of disorders • Males and females affected • Some genes now identified* – but account for only 10% of patients • * ICOS, CD19, TACI, BAFF-R

17. Antibody deficiency • Easy to make the diagnosis • Critical issue – THINK of possibility

18. Case history 3 . • PO, aged 20 years • Recurrent bacterial infections, early childhood • Tuberculosis, disseminated aged 6 years • Brother with similar history died from brain inflammatory disorder

19. Antibody deficiency 3. Diagnosis - • Hyper IgM syndrome • Absent IgG, IgA • Fail to switch IgM to other Ig classes

20. CD40 ligand B T h CD40 ligand Cytokines - IL-4, 5, 6

21. Hyper-IgM - HIGM • Patients may have elevated IgM levels • Low levels of IgG, IgA • Cause - CD40 ligand deficiency • Incidence < 1: million

22. CD40 ligand T h Macroph APC CD40 ligand Cytokine – IFN-gamma

23. HIGM - infections Major cause of morbidity and mortality • Pyogenic bacteria Also - “Opportunistic” infections - • Pneumocystis carinii • Cryptosporidium parvum - in drinking water • Toxoplasma gondii

24. Hyper-IgM - infections RISKS - • Cryptosporidiosis - protozoa - in farm animals, milk, water; toxin released • Can cause chronic biliary inflammation • Boiled/filtered drinking water

25. Case history 4 • 1 year old boy • Recurrent chest infections - viral, fungal, bacterial • Constantly in hospital • Severe “failure to thrive” • Blood tests - low lymphocyte count

26. T cell immunodeficiency • Severe combined immunodeficiency - SCID • 9 different molecular causes

28. T cell immunodeficiency • Rare - 1: 100 000 • X-linked - commonest - 60% of SCID • Males • Rapidly fatal • Emergency bone marrow transplantation

29. Early diagnosis important SYMPTOMS - • Present early - by 3 months • Oral candidiasis • Lung inflammation “pneumonitis” • Diarrhoea • Failure to thrive !!!

30. SCID • Various molecular causes • X-linked form - absence of gamma chain in cytokine receptor - commonest form • Defect in IL-7 function

31. SCID - molecular defects

32. X-linked SCID • commonest form X-linked - Xq 13.1-13.3 - 60% cases • common chain defective • same  chain in IL-2, IL-4, IL-7, IL-9, IL-15, IL-21 receptors.

33. X-linked SCID g chain gene - for cytokine receptors

34. SCID - diagnosis • Absence of T cells • Some - absent B and/or NK cells • Low immunoglobulins

35. SCID - treatment Medical Emergency • Isolation - negative pressure environment • Immunoglobulin replacement • Bone marrow transplant - curative 80% • Gene therapy - works but ……. leukaemia

36. Gamma chain deficient SCID - gene therapy • Gene therapy successful in > 10 patients. Complete restoration of T cell populations, restored Ig production - • but 2 patients developed leukaemia • Alain Fischer, Science 2000, NEJM 2002

37. Case history 5. • JN - 25 year old male; female siblings and one brother a/w. • History of skin abscesses - Staph aureus • Lung and liver abscesses - Pseudomonas, Serratia marcesens • Lung abscess, extending to spinal cord - Aspergillus

38. Chronic granulomatous disease • Note cervical nodal abscess • Gingivitis and periodontitis • Abscess indenting the oesophagus

39. Chronic Granulomatous Disease • Staph aureus • Burkholderia cepacia • Serratia marcescens • Nocardia • Aspergillus

40. Case history 5. • Lung surgery - lobectomy • Spinal surgery • Paralysis on left side - temporary • 4 month hospitalisation • Now well

41. Chronic Granulomatous Disease

42. Oxidative Burst Flow Cytometry • Flow cytometric assay • Neutrophils separated • Stimulate with Phorbol Myristate Acetate • Reduce DHR • Shift in immunoflourescence

43. Immunodeficiency - causes …. lymphocytes neutrophil APCs T cell Complement proteins B cell

44. Multiple cells of the IS

45. Case 6 – 17 year old male History • Normal health until 1 month ago • Acute episode of headache, neck stiffness • Hospital admission – meningococcal meningitis • Treated with antibiotics – full recovery

46. Case 4 – 17 year old male History - continued • 3 weeks later, second episode of headache, diminished consciousness • Hospital admission, CSF sample, meningococcus identified • Failed to respond to treatment, died

47. Fatal C7 deficiency C1 C4, C2 C3 C5 C6 C7 C8,9 LYSIS 17 year old boy with 2nd episode of Meningococcal meningitis

48. Immunodeficiency - when to suspect? Infections • Recurrent – sinus, lungs • abscesses; brain • Atypical • Atypical mycobacterium e.g. M. avium • Opportunistic organisms eg. Pneumocystis carinii – in T cell defects

49. Immunodeficiency - when to suspect? Syndrome features - • diGeorge – cardiac, facial, metabolic (calcium) • Wiskott-Aldrich – eczema, bleeding (low platelets, X-linked • Ataxia-telangiectasia

50. Classification of Immunodeficiency states • Primary - intrinsic defect in immune system - many genes now identified. • Secondary - known causative agent eg. HIV virus, drug