EFFECTS OF STEROIDS ON THE LUNG ACCUMULATION OF NEUTROPHIL AND MONOCYTE IN RABBITS WITH ENDOTOXEMIA

Study objective: To determine the effects of steroids on the lung accu mulation of polymorphonuclear leukocytes (PMNs) and monocytes in rabbi ts with endotoxemia. Design: A prospective, randomized, controlled ani mal trial. Setting: Surgical research laboratory, Keio University Scho ol of Medicine. Subjects: Twenty-four female Japanese white rabbits, I nterventions: Rabbits with endotoxemia were pretreated with steroids s ufficient to inhibit the production of tumor necrosis factor (TNF) and to prevent the fall of BP. Measurements and results: The circulating leukocyte counts and the leukocyte accumulation in the lung were evalu ated. Endotoxin caused a rapid decrease in circulating PMNs and monocy tes followed by an 8-fold greater accumulation of PMNs (p<0.001) and a 6.5-fold greater accumulation of monocytes (p<0.05). Steroids failed to inhibit this initial drop of PMNs and monocytes. However, steroids inhibited the PMN accumulation in the lung by 50% (p<0.05), without in hibiting the monocyte accumulation in the lung. Conclusions: These fin dings suggest that the lung accumulation of PMNs is dependent on TNF o r other inflammatory mediators that are inhibited by steroids while th e lung accumulation of monocyte is not.