Human lymphocytes synthesize C-reactive protein

We obtained evidence for the synthesis and secretion of C-reactive protein (CRP) by peripheral mononuclear cells in culture. Human mononuclear cells isolated from peripheral blood, after depletion of platelets, were cultured in glutamine-depleted RPMI 1640 supplemented with [3H]glutamine in the presence of 10-O-tetradecanoyl-phorbol-13-acetate (TPA). Anti-CRP antiserum was added to the culture medium, and the resultant immunoprecipitate was analyzed in SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The immunoprecipitate consisted of CRP, heavy and light chains of IgG, and only the CRP protein band had radioactivity, indicating that CRP was synthesized by mononuclear cells. In the populations of mononuclear cells, T-cell preparations mainly synthesized CRP, under stimulation of a factor derived from activated monocytes. Studies using the inhibitors of phospholipid metabolism suggested that generation of the monocyte factor was relevant to metabolites of an arachidonate cascade.