Femur fracture induces site-specific changes in T-cell immunity

Background. Trauma is associated with altered host defense and susceptibili ty to infection, in part due to cytokine dysregulation and altered T-cell i mmunity. The gut-associated lymphoid tissue (GALT) provides a defense again st infection and contributes to the process of mucosal healing by T-cell ac tivation and cytokine production. Objective. To determine whether femur fracture induces alterations in Peyer 's patch and splenic T-cell phenotype, proliferative response, and cytokine expression following traumatic injury. Methods. Mice underwent femur fracture or sham procedure and, 48 h later, l ymphocytes were isolated from spleen and Peyer's patches. Lymphocytes were cultured, and lipopolysaccharide (10 mu g/ml) was added in some cultures. C ells and supernatant were harvested at 48 h. Proliferation was analyzed by [H-3]thymidine, and interleukin-10 (IL-10) protein was measured by ELISA in the culture supernatant. T-cell phenotype was determined by flow cytometry . Results. Femur fracture induced a significant increase in proliferative res ponse in Peyer's patch immunocytes. In contrast, no significant differences were identified in splenocyte proliferative response 48 h after femur frac ture injury. Femur fracture induced a significant decrease in IL-IO protein expression of both splenocytes and Peyer's patches. Femur fracture also in duced a significant increase in the fraction of CD3(+), CD4(+), and T-cell receptor-alpha beta Peyer's patch immunocytes, whereas splenocytes demonstr ated no significant phenotypic change. Conclusion. Femur fracture is associated with significant alterations in Pe yer's patch but not splenic T-cell phenotype and proliferative response ear ly (48 h) after injury. Changes in the GALT immune response may contribute to intestinal mucosal dysfunction and increased susceptibility to gut-deriv ed sepsis after traumatic injury. (C) 1999 Academic Press.