B or T cell disorders

Question 1

Selective IgA deficiency

Answer 1

Defect: unknown, most common primary immunodeficiency
Presentation: Majority are asymptomatic, Airway and GI infections, AI disease, Atopy, Anaphylaxis to IgA-containing products (blood)
Findings: Decreased IgA with normal IgG/IgM

Question 2

Common variable immunodeficiency

Answer 2

Defect: defect in B cell differentiation, many causes
Presentation: Can be acquired in 20s-30s, increased risk of autoimmune disease, bronchiectasis, lymphoma, sinopulmonary infections
Findings: decreased plasma cells, decreased immunoglobulins

Question 3

Thymic aplasia (DiGeorge syndrome)

Answer 3

Defect: 22q11 deletion; failure to develop 3rd and 4th pharngeal pouches, absent thymus and parathyroids
Presentation: Tetany (hypocalcemia), recurrent viral/fungal infections (T-cell deficiency), conotruncal abnormalities (tetralogy of Fallot, truncus arteriosus)
Findings: Decreased T cells/PTH/Ca, absent thymic shadow on CXR, 22q11 deletions detected by fish.

Question 4

IL-12 Deficiency

Answer 4

Defect: decreased Th1 response, autosomal recessive
Presentation: Disseminated mycobacterial and fungal infections, may present after BCG vaccine administration
Findings: decreased IFN-gamma

Question 5

Autosomal dominant hyper-IgE syndrome (Job syndrome)

Answer 5

Defect: deficiency of Th17 due to STAT3 mutation –> impaired recruitment of neutrophils to sites of infection
Presentation: FATED-coarse Facies, cold-noninflamed staphylococcal Abscesses, retained primary Teeth, increased IgE, Dermatologic problems (eczema).
Findings: increased IgE, decreased IFN-gamma, increased eosinophils

Question 6

Chronic mucocutaneous candidiasis

Answer 6

Defect: T-cell dysfunction, many causes
Presentation: noninvasive Candida albicans infections of skin and mucous membranes
Findings: absent in vitro T-cell proliferation in response to Candida antigens, absent cutaneous reaction to Candida antigens.

Question 7

X-linked (Bruton) agammaglobulinemia

Answer 7

Defect: Defect in BTK (tyrosine kinase) –> no B cell maturation, X-linked recessive
Presentation: Recurrent bacterial and enteroviral infections after 6 months (decline in maternal IgG).
Findings: absent B cells in peripheral blood, decrease Ig of all classes. Absent/scanty lymph nodes and tonsils