Effects of sulindac on in vitro immunologic function and on prostaglandin production by human peripheral blood...

Prostaglandins (PG) appear to regulate immune-mediated inflammation, but the mechanisms involved remain unclear. Several families of nonsteroidal antiinflammatory drugs (NSAID) have been observed to inhibit PG synthesis. Among these drugs, sulindac sulfide is a potent inhibitor of PG production while its parent pro-drug, sulindac sulfoxide (sulindac), lacks PG synthesis inhibitory activity in cell-free systems. We have studied the effects of sulindac sulfoxide on the blastogenic response of human peripheral blood mononuclear cells (PBMC) stimulated by exposure to alloantigens and mitogens in vitro. Sulindac inhibited proliferation of activated PBMC in a dose-dependent manner but had little effect on the proliferation of unstimulated cells. The inhibition of mitogen-induced blastogenesis correlated with both the uptake of radiolabeled drug and the inhibition of in vitro production of PG (PGE and PGF) by mitogen-activated PBMC. These data indicate a functional relationship between PG synthesis and immune cell activation which may also apply to PBMC activated in vivo by autoimmune disease. Metabolism of sulindac sulfoxide by PBMC in vitro produced too little sulindac sulfide to adequately explain the inhibition of PG production. These data suggest that immunomodulation by sulindac may be due to a direct inhibition of cellular activation. Thus, it is proposed that decreased PG production may be a result rather than the cause of the hypoproliferative response.