Altered T cell cytokine production following mechanical trauma.

BACKGROUND Cell mediated immunity is suppressed following traumatic injury. The Objective is to determine whether there is a shift from T helper type 1 (TH1) to TH2 cell cytokine production following mechanical trauma in a rat model. METHODS Male Sprague-Dawley rats were anesthetized and subjected to bilateral femur fractures or sham injury. Spleens were removed 3 days later. T cell proliferation and cytokine production were stimulated by culturing spleen cells with the T cell mitogen concanavalin A (con A). Interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-10 and IL-4 concentrations were measured in spleen cell supernatants using enzyme linked immunosorbent assays. RESULTS Con A-induced spleen cell proliferation was decreased in traumatized rats compared to controls (p < 0.05). Spleen cell supernatant concentrations of the TH1 cytokines IL-2 and IFN-gamma were decreased in the trauma group (p < 0.05). Supernatant concentrations of the TH2 cytokine IL-10 were also decreased in traumatized rats (p < 0.01). The IL-4 concentrations were below the detection limit (< 15 pg/mL) in all cell supernatants. CONCLUSIONS Mechanical tissue injury leads to generalized suppression of T helper cell cytokine production rather than a shift from TH1 to TH2 cell activity. Post-trauma cellular immunosuppression is not mediated via excess IL-10 production by TH2 cells.