Procoagulant Activity of Rabbit Peritoneal WBC: Effects of Cortisone and Endotoxin

Abstract

This study tested the hypothesis that cortisone increases the procoagulant activity of WBC of rabbits injected with endotoxin. Rabbits were given either saline (control) or cortisone acetate, 25 mg daily for 5 days intramuscularly. On day 5, animals received intravenously either 1 ml of saline or of E. coli endotoxin, 100 μg/kg. Peritoneal leukocytes were collected 1 hour (h) later. Two types of suspensions were prepared following intraperitoneal starch:primarily heterophils (16 h after starch), primarily macrophages (72 h after starch). Suspensions were washed, counted, and examined for clotting activity in a one-stage thromboplastin time assay. Activity was expressed in units (U) from a reference curve made with rabbit brain thromboplastin (clotting time of 1/10 dilution, 12.6 sec = 100 U). Heterophil suspensions were tested at approximately 60,000 WBC per mm3. After incubation in Hank’s solution at 37° for 30 min they gave the following results:saline-saline, 1.8 U;cortisone-saline, 0.6 U;saline-endotoxin, 7.8 U;cortisone-endotoxin, 5.3 U. Sonicated suspensions were also tested and possessed markedly decreased activity. Incubated macrophage suspensions were tested at different concentrations:saline-saline (30,000 per mm3) 3.1 U;cortisone-saline (15,000 per mm3) 0.7U; saline-endotoxin (14,000 per mm3) 51.8 U; cortisone-endotoxin (6,000 per mm3) 82.2 U. Sonicated macrophages from endotoxin-treated animals retained potent procoagulant activity.Thus, endotoxin induces WBC procoagulant activity primarily in macrophages rather than heterophils. Activity is greatest in macrophage suspensions from cortisone-treated animals.