Interleukin-2 increases the oxidative activity and induces migration of murine polymorphonuclear leukocytes in vivo.

Since recombinant human interleukin-2 (IL-2) can protect mice from a lethal bacterial challenge and can induce a vascular leak, we investigated the effects of IL-2 on the oxidative metabolism and migration of murine polymorphonuclear leukocytes (PMN) in vivo. To assess oxidative activity of PMN, we used luminol-dependent chemiluminescence (CL) to measure oxygen radical formation after stimulation of the PMN with phorbol myristate acetate (PMA). We demonstrated that single IP doses of IL-2, from 0.2-3 mg/kg, could significantly increase CL from peripheral blood PMN obtained after IL-2 treatment. The increase of PMN-CL induced by IL-2 in vivo reached a maximum 4.5 fold increase at 3 and 6 h after IL-2 treatment. At 1, 12, and 24 h after rIL-2 treatment, there were no changes in CL and PMN activity remained within normal limits. Intraperitoneally administered IL-2 also caused a significant influx of PMN into the peritoneal cavity. IL-2 increased the percentage of PMN among the peritoneal exudate cells from a control baseline level of less than 1% to 18% PMN after IL-2 treatment. These data that demonstrate the capacity of IL-2 to augment the function and metabolism of PMN in vivo and illustrates the broad range of effects of IL-2 on the immune system in vivo and may explain in part the protective effects of IL-2 in experimental bacterial infections and the possible role of PMN in the systemic toxicities induced by IL-2.