Glucocorticoid-induced low molecular mass anti-inflammatory factors which do not inhibit phospholipase A2

The peritoneal lavage fluid of dexamethasone (DXM)-pretreated rats was filtered through an Amicon YM-10 membrane (cutsize 10 kD). The retentate inhibited dextran oedema. Its 40 kD fraction (lipocortin) obtained by molecular sieving on Sephadex (SG)-75, suppressed carrageenin-induced foot swelling and phospholipase A2 (PLA2) activity, but it had no effect on the dextran response. The Amicon filtrate was chromatographed on SG-25 gel and yielded 6 and 2 kD fractions suppressing dextran and serotonin (5-HT) oedema but not carrageenin inflammation and PLA2 activity. These fractions may be active fragments of vasocortin, a glucocorticoid-induced mediator regulating vascular permeability.