THE ROLE OF INTERLEUKIN 6 IN INTERFERON-γ PRODUCTION IN THERMALLY INJURED MICE

Abstract

Following traumatic injury, patients suffer from compromised immunity increasing their susceptibility to infection. Previous studies from this laboratory demonstrated that female BALB/c mice subjected to a 15% total body surface area (TBSA) scald injury exhibit a decrease in cell-mediated immunity 10 days post-burn. Studies described herein revealed that concanavalin A (Con A; 2μg/ml)-stimulated splenocytes from sham treated animals produced 3557±853pg/ml of IFN-γ while splenocytes from burn injured animals released two-fold more cytokine (P<0.05). To determine whether leukocyte production of IFN-γ was under the influence of macrophages, splenic macrophage supernatants generated from burned animals were incubated with splenic lymphocytes from sham and burn animals. The amount of IFN-γ released by lymphocytes from sham animals increased when cultured with macrophages from burned mice (P<0.05). This suggests that the increase in IFN-γ production by unfractionated splenocytes in burned mice relative to sham treated animals is macrophage-dependent. Macrophage supernatants from burned mice released twice as much IL-6 as supernatants from sham animals (P<0.05), and when IL-6 was blocked in vivo, the amount of IFN-γ production in burned mice decreased to sham levels (P<0.05). Thus, IL-6 mediates IFN-γ production following burn.