Hydrocortisone and 'macrocortin' inhibit the zymosan-induced release of lyso-PAF from rat peritoneal leucocytes.

Hydrocortisone and the glucocorticoid-induced anti-phospholipase protein macrocortin, were tested as inhibitors of PAF generation. The steroid produced a dose-dependent inhibition of the release of the PAF precursor 2-lyso-PAF, and this effect was mimicked by affinity-purified macrocortin. Neither agent had any effect on the acetylation of lyso-PAF to PAF. Of other drugs tested only phospholipase inhibitors blocked lyso-PAF release and sulphydryl reagents blocked the acetylation step. It is concluded that glucocorticoids inhibit the generation of PAF and this could be an important component of their anti-anaphylactic and anti-inflammatory action.