Immunoglobulins (Ig) are obtained by fractionation and subsequent viral inactivation of pooled plasma from thousands of blood donors. These blood products contain predominately human IgG, as well as variable amounts of human IgM and IgA. Nonspecific Ig can be administered as subcutaneous infusion (SCIG) or as intravenous infusion (IVIG); IM injections are rarely used. The method of storage and shelf life are specified by the manufacturer and may vary between products.
Indications for Ig replacement therapies include congenital and acquired Ig deficiency states. However, indications beyond immunodeficiencies are vast and extend to a number of hematologic, transplant, rheumatologic, neurologic, dermatologic, and infectious indications, where Ig have an immunomodulatory effect.