Inhibitory and disruptive effects of some antirheumatics on antigen-antibody complexes

Purified antibodies to human serum albumin or to human gamma-globulin were used to study the direct influence of some antirheumatic drugs on the formation and disruption of immunoprecipitates. 125I-labelled human serum albumin and 125I-labelled human IgG served as indicators. The effects of the following drugs were described: diclofenac, monophenylbutazone, diphenylbutazone, ibuprofen, and metamizol. At approximately therapeutic concentrations, the antirheumatics inhibited the formation of complexes of homologous antibodies with human serum albumin and, surprisingly, with human IgG. When the antigens were precipitated with antibodies, subsequent addition of the antirheumatics to the preformed immunoprecipitates caused disruption of [125I]human serum albumin-anti-human serum albumin precipitates but practically no disruption of human [125I]IgG-anti-human IgG precipitates. These new findings may be of relevance for clinical diagnosis and therapy as well as for research in immunochemistry. It is conceivable that, in patients, antirheumatic or other drugs might interfere with immunological determinations of clinico-chemical quantities. Interference of drugs with antigen-antibody reactions might also help to explain some beneficial effects or undesirable side effects of certain drugs.