Gammaglobulins

Gammaglobulins are a broad group of immunoglobulins that comprise the gamma fraction of blood serum proteins. They are produced by plasma cells, which are mature B lymphocytes, and are responsible for the body's antibody-mediated immune response. In laboratory tests, gamma globulins are identified as the gamma region in serum protein electrophoresis.

Immunoglobulins, or antibodies, fall into five major classes: IgG, IgA, IgM, IgD, and IgE. IgG is the most abundant in serum and provides targeted systemic immunity; IgA is concentrated in mucosal areas and secretions; IgM serves as a first responder during acute exposure; IgD functions mainly as a B cell receptor; and IgE is involved in allergic reactions and defense against parasites. The different classes have distinct roles in recognizing and neutralizing pathogens.

Clinically, serum gammaglobulin levels are measured to evaluate humoral immunity. Hypogammaglobulinemia (low gammaglobulins) can lead to recurrent infections and is seen in primary immunodeficiencies (such as common variable immunodeficiency) and secondary conditions. Hypergammaglobulinemia (elevated gammaglobulins) can occur with chronic infections, autoimmune diseases, liver disease, or certain monoclonal gammopathies.

Therapeutically, gammaglobulin preparations are available as intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG) and are derived from pooled human plasma. They provide passive immunity and are used in various settings, including primary and secondary immunodeficiencies and certain autoimmune or inflammatory diseases. Safety considerations include infusion reactions, rare transfusion-related events, and, in IgA-deficient patients, risk of anaphylaxis or reactions due to anti-IgA antibodies.