A preparation of plasma proteins derived from the pooled plasma of adult donors. Largely comprised of IgG antibodies, therapeutic immune globulin provides passive immunization by increasing the recipient's serum levels of circulating antibodies. IgG antibodies have multiple functions, including binding to and neutralizing bacterial toxins; opsonization of pathogens; activation of complement; and suppression of pathogenic cytokines and phagocytes through binding to CD5, interleukin-1a (IL-1a), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and T-cell receptors. Therapeutic immune globulin may diminish pathogenic mechanisms in some autoimmune diseases by binding to and inhibiting the activity of autoantibodies.