ELEVATED MONOCYTE INTERLEUKIN-6 (IL-6) PRODUCTION IN IMMUNOSUPPRESSED TRAUMA PATIENTS .1. ROLE OF FC-GAMMA-RI CROSS-LINKING STIMULATION

This study demonstrates that immunodepressed trauma patients' monocytes produce elevated interleukin-6 to adherence, bacterial, and cytokine stimulation compared to immunocompetent trauma patients' or normals' monocytes, suggesting their in vivo preactivation possibly mediated by the hyperimmunoglobulinemia which characterizes these patients. Furthermore, stimulation of monocytes through cross-linking their Fc-gamma-RI induces and augments interleukin-6 (IL-6) production to subsequent stimulation both in trauma patients' (P < 0.001) and in normals' (P < 0.001) monocytes. As we reported earlier, immunodepressed trauma patients have an increased proportion of Fc-gamma-RI-bearing monocytes in their total monocyte population and here we show that those Fc-gamma-RI+ monocytes produce significantly elevated interleukin-6, suggesting a relationship between elevated monocyte interleukin-6 production and Fc-gamma-RI triggering. Interleukin-6 induction by FcRI stimulation is not mediated solely by FcRI-induced MO tumor necrosis factor-alpha, IL-1-alpha, or IL-1-beta production and is independent of MO prostaglandin E2 levels. Therefore, FcRI stimulation-induced elevated MO IL-6 might contribute to the increased immunoglobulin levels posttrauma.