[Diagnostic orientation in case of abnormal plasma immunoglobulins (excluding IgE)]

Serum immunoglobulins abnormalities may be qualitative or quantitative. So called benign IgG or IgA monoclonal gammopathy may be associated with certain rare clinical entities such as mucinar papulosis or leakage syndrom. Monoclonal IgM are mostly observed in patients with lymphoplasmacytic malignant proliferation; monoclonal IgM frequently posess a defined antibody activity which may be related to clinical symptoms such as hemolysis, cryoglobulinemic purpura or peripheral neuropathy. When a lymphoplasmacytic disease can be excluded, hypogammaglobulinemia is usually genetic, although rare causes of acquired hypogammaglobulinemia exist. Selective humoral deficiencies mostly of IgA or IgG2 may be missed on routine study of the serum. A marked hypergammaglobulinemia is observed in infectious or parasitic diseases, autoimmune disorders or certain lymphoid proliferation such as angioimmunoblastic lymphadenopathy. The presence of a monoclonal IsG or IsA morrate the need of a careful evaluation to second a malignand localized or gone marrow plasmacytic proliferation.