Gold and modulation of the immune response.

The effects of gold on immune responses are reviewed. Gold salts used therapeutically can be followed by a decline in serum immunoglobulin levels, and rheumatoid factor titers in rheumatoid arthritis; in pemphigus there is similarly a drop in anti-epithelial antibody titers. Gold inhibits stimulation of immunoglobulin-secreting cells. Gold inhibits the activation of the classical and alternate complement pathways. Gold compounds inhibit numerous cell-mediated immune responses to various mitogens and antigens. Inhibition may be due to the effect of gold on macrophages acting as helper cell in these reactions. Auranofin is a new oral compound which seems to be particularly potent in its immuno-regulatory actions; it differs from other gold compounds in its pharmacokinetics, and in the nature of its ligand. Gold has also been reported to enhance certain immune reactions. The extent of the immuno-regulatory effects of gold in vivo is unknown, and the relation of these effects to its therapeutic actions remains to be clarified.