[Deficiencies in humoral immunity]

B cell immune deficiencies are characterized by inadequate production of antibodies and/or low levels of one or more classes of immune globulins (IgG, IgA, IgM) or IgG sub-classes. They include: 1) severe deficiencies involving all the immune globulins (Bruton agammaglobulinemia, variable hypogammaglobulinemia); 2) selective deficiencies in immune globulins (IgA deficiency, IgM deficiency, deficiencies in IgG sub-classes, dysgammaglobulinemias); 3) transient infantile hypogammaglobulinemia; 4) B cell immune deficiencies with normal gammaglobulin levels. Symptoms of B cell immune deficiencies are variable but respiratory manifestations are usually more prominent than the other features that include digestive disorders, fungal infections, autoimmune conditions, joint manifestations, and severe bacterial or viral infections (pneumococcus, meningococcus, enterovirus). Management of IgM and IgA deficiencies rests on antimicrobial agents and non-specific measures. The prognosis of the other B cell immune deficiencies has improved dramatically since effective replacement immune globulin therapy has become available; this treatment combined with antimicrobial therapy and chest physiotherapy can usually prevent development of bronchiectases. The main risk is chronic enteroviral neuromeningeal infection.