Effect of platelet-activating factor (PAF-acether) and its specific receptor antagonist, BN 52021, on interleukin 1 (IL1) release and synthesis by rat spleen adherent monocytes.

PAF-acether, at doses ranging from 1pM to 0.1 microM did not induce a significative release and/or synthesis of IL1 from monocytes. In contrast, depending upon the dose of the mediator, adverse effects on the lipopolysaccharide (LPS)-induced IL1 release and synthesis were observed. PAF-acether at 1pM increased IL1 release by 120 +/- 39% and synthesis by 87 +/- 27% whereas at 0.1 microM a decrease of IL1 release of 52 +/- 9% and synthesis of 46 +/- 6% were observed. BN 52021, a specific PAF-acether receptor antagonist, reversed by more than 70% the increase of inhibition of LPS-induced IL1 release and synthesis induced by 1pM and 0.1 microM of the autacoid, respectively. No direct effect of BN 52021 on IL1 release and synthesis from adherent monocytes was noted. These results indicate that PAF-acether modulates monocytes functions, possibly via specific binding sites.