No abstract

The effect of chloroquine (CQ) on the ability of normal human peripheral blood monocytes to produce a soluble mononuclear cell factor (MCF) capable of stimulating prostaglandins from adherent rheumatoid synovial cells was studied. CQ inhibited concanavalin A (Con A)-and bacterial peptidoglycan-induced MCF activity, but not colchicine-induced activity, in a dosedependent manner. After incubation with CQ for 20 minutes, ' H Con A binding was reduced by 50% ; and metabolism of pre-bound ' H Con A was inhibited. These data suggest that CQ can inhibit MCF production by inhibition of lectin binding, perhaps by inhibition of receptor recycling.Soluble peptide mediators originating from mononuclear cells are clearly important for communication among immunocompetenl cells. In addition, such mediators affect cells not classically considered to be immunocompetent, such as fibroblasts.Dayer et al (1) have described one such mediator produced by monocytes. which can markedly stimulate the production of prostaglandin E2 (PGE2) ~_ _ From the