SUPPRESSOR MONOCYTES IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS - EVIDENCE OF SUPPRESSOR ACTIVITY ASSOCIATED WITH A CELL-FREE SOLUBLE PRODUCT OF MONOCYTES

Abstract

Abnormal SLE [systemic lupus erythematosus] mononuclear cell responses to PHA [phytohemagglutinin] can be corrected by removal of adherent mononuclear cells. In this study cell-free supernatants from allogeneic adherent cell cultures inhibited lymphocyte response and addition of indomethacin to cultures partly blocked the inhibitory effect of the resulting supernatant. Supernatants from SLE monocyte cultures suppressed allogeneic normal T [thymus-derived] cell responses by 36% (response in supernatant 33,515 .+-. 3814 cpm, media control 51,947 .+-. 3173 cpm), but normal monocyte culture supernatants did not suppress (48,384 .+-. 4172 vs. 47,477 .+-. 3221 cpm). Early (< 24 h) addition of indomethacin to monocyte cultures prevented elaboration of inhibitory material. In normals, indomethacin-treated supernatants were strikingly stimulatory (response 178% .+-. 24 of control), whereas similarly treated supernatants of SLE monocyte cultures were not stimulatory (response 103% .+-. 8 of control). A soluble inhibitor of lymphocyte blastogenesis is apparently produced by SLE monocytes.