Standard and Special Human Immune Serum Globulins as Therapeutic Agents

Human γ-globulin is a valuable and frequently prescribed biological used to provide passive immunity against microbial agents, toxins, or cells. γ-Globulin is most widely used for the short-term prevention of certain bacterial or viral diseases when active immunization is unavailable (eg, hepatitis A) or when active immunization has not been given before exposure (eg, tetanus, rabies). γ-Globulin is also indicated on a continuous basis in replacement therapy for persons with antibody immunodeficiency. It is also (mis)used by many physicians for colds, allergies, and recurrent infection despite lack of proved efficacy. Two types of γ-globulin preparations are available: standard human immune serum globulin (HISG) for general use, and special human immune serum globulins with a known antibody content for specific illnesses (Table I). In addition, certain animal sera and antitoxins are available for passive immunity (Table I). Although a discussion of these agents is beyond the scope of this review, it is important to emphasize that their use is associated with considerable risk of adverse side reactions (anaphylaxis and serum sickness). Accordingly, the physician should know the exact indications for their use, always institute sensitivity testing, and be ready to treat side reactions immediately.1 SOME PROPERTIES OF IgG GLOBULIN The immunoglobulins or "γ-globulins" are the proteins of the plasma and tissue made in lymphoreticular tissues which have antibody activity.2 Although there are six classes of immunoglobulin—IgG, IgM, IgA, IgD, IgE, and secretory IgA—only IgG is present in significant quantities in HISG. IgG is a glycoprotein with a molecular weight of 150,000 daltons distributed equally between the serum and the tissues.