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

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

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.

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

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

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

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

Primary immuno-deficiency Case histories

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

BB - patient with XLA

Essential role of BTK

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

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

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

CT scan of lung - bronchiectasis

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

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

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

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

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

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

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

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

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

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

T cell immunodeficiency Severe combined immunodeficiency - SCID 9 different molecular causes

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

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

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

SCID - molecular defects

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

X-linked SCID  chain gene - for cytokine receptors

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

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

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

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

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

Chronic Granulomatous Disease Staph aureus Burkholderia cepacia Serratia marcescens Nocardia Aspergillus

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

Chronic Granulomatous Disease

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

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

Multiple cells of the IS

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

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

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

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

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

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