The commonest primary immunodeficiency is: (A) Common variable immunodeficiency, (B) Isolated IgA immunodeficiency, (C) Wiskott-Aldrich syndrome, (D) AIDS
Answer is B. Isolated IgA deficiency Extremely low levels of serum & secretory IgA (may be IgG2 & IgG4 too) Defective differentiation of B cells to IgA producing plasma cells CF Mucosal immunity affected Recurrent sinopulmonary infections & diarrhoea When transfused with blood containing IgA may develop fatal anaphylactic reactions