No effect of recombinant human interleukin-1 on numbers of peripheral blood and peritoneal leukocytes during acute inflammation

Abstract

Recombinant human interleukin-1 (IL-1) can prolong the survival of mice with severe systemic bacterial or fungal infections. In order to assess whether this is due to an effect of IL-1 on the production of leukocytes or their migration to the site of infection, the influence of IL-1 on the influx of leukocytes to the site of an acute inflammation was studied in normal and in granulocytopenic mice. The numbers of granulocytes, lymphocytes, and monocytes or macrophages in both the circulation and the peritoneal cavity were determined during an acute sterile inflammation elicited by intraperitoneal injection of either newborn calf serum (NBCS) or heat-killed Candida albicans, and during a peritoneal infection with viable C. albicans. After normal mice were injected intraperitoneally with NBCS or 10(7) CFU heat-killed or viable C. albicans, the number of peritoneal granulocytes rose sharply within 6 h. Pretreatment of mice with a single intraperitoneal dose of 80 ng IL-1 24 h before injection of an inflammatory stimulus did not influence the course of the numbers of leukocytes in the circulation or in the peritoneal cavity. When mice were rendered granulocytopenic by cyclophosphamide, both the influx of granulocytes into the peritoneal cavity and the concomitant rise in the number of peripheral blood granulocytes after injection of NBCS, killed or viable C. albicans was virtually absent. Pretreatment of granulocytopenic mice with IL-1 did not influence the course of the numbers of leukocytes in either the circulation or the peritoneal cavity. These findings show that the beneficial effect of a single dose of IL-1 on the course of candidal infections in normal or granulocytopenic mice is not attributable to the influx of granulocytes or monocytes.