Decreased pokeweed mitogen-induced IgM and IgM rheumatoid factor synthesis in rheumatoid arthritis patients treated with gold sodium thiomalate or penicillamine.

Prospective and retrospective analysis of data obtained on 119 patients with rheumatoid arthritis suggested a relationship between clinical response induced by gold salts or D-penicillamine and decreased in vitro antibody synthesis by peripheral blood mononuclear cells. A subgroup of 21 patients with inactive disease receiving these drugs was found to have decreased pokeweed mitogen-induced in vitro synthesis of IgM and IgM rheumatoid factor. Detailed analysis of the cellular mechanisms responsible for this decreased responsiveness demonstrated markedly decreased B cell function. Patients treated with D-penicillamine also had altered T cell helper function manifested by incomplete reconstitution of the normal IgM response, while patients treated with gold salts had normal T cell function. Monocytes appeared not to have a major role in the decreased in vitro responsiveness. The results suggest that, in patients who respond to gold salts or D-penicillamine, antibody synthesis by circulating B cells is profoundly decreased, probably due to an indirect effect of these disease-modifying agents.