Polymicrobial sepsis following trauma inhibits interleukin-10 secretion and lymphocyte proliferation.

Immune competence declines following major injury, and predisposes the trauma patient to infection. Interleukin-10 (IL-10), although an immunosuppressive cytokine, is also important in the initiation of immune responses. This study investigated alterations in IL-10 and immune function associated with polymicrobial sepsis following trauma using murine femur fracture (FFx) and cecal ligation/puncture (CLP) models. Mice were randomized to Normal, FFx, Alcohol and FFx (EtOH + FFx), CLP, FFx + CLP, and EtOH + FFx + CLP. Polymicrobial sepsis was induced by performing CLP 4 days after FFx, and animals were killed 14 days later; immune function was assessed by in vitro splenocyte cultures. Lymphocyte proliferative responses were significantly suppressed in FFx and CLP animals. Splenocyte IL-10 production was significantly reduced in FFx and CLP animals, with concurrent increases in nitrite and tumor necrosis factor release. This study documents that trauma induces alterations in the inflammatory cytokine cascade that affect the immune response to subsequent septic challenges.