Splenic suppressor cells in adjuvant arthritic rats: effect of D-penicillamine

Adherent spleen cells from rats with adjuvant arthritis inhibit the incorporation of 3H-thymidine into DNA and 3H-leucine into protein in nonadherent spleen lymphocytes, stimulated by the mitogens Concanavalin A and E. coli Lipopolysaccharide. This suppressive activity was abolished by pretreatment of the adherent cells with the selective macrophage toxin silica. It is suggested that suppressor macrophages directly, or through interaction with suppressor T cells, inhibit the response of lymphocytes to mitogens by inhibition of cellular protein synthesis, followed by inhibition of DNA-synthesis and death of about 30% of the lymphocytes. Treatment of adjuvant arthritis rats with D-penicillamine resulted in significantly increased incorporation of 3H-thymidine in spleen lymphocytes, compared to cultures from untreated, arthritic rats. This approach may prove useful in the investigation of cellular interactions in a model of immunologically induced inflammation and provide a tool for the evaluation of the effects of immunoregulatory drugs.