Posttraumatic lymphocyte response: A comparison between peripheral blood T cells and tissue T cells

Background: T-cell response to trauma has been assessed primarily by sampling peripheral blood lymphocytes. We hypothesized that lymphocytes residing in tissue and traveling through lymph vessels are more likely to be activated by tissue injury and hemorrhage-induced hypoperfusion.We compared peripheral blood T-cell response with tissue or lymph T-cell response in an ovine model of multiple injury. Methods: Anesthetized adult sheep instrumented with a chronic prefemoral lymph fistula were subjected to lower-extremity fractures, fixed-volume hemorrhage, resuscitation, and fracture stabilization. Peripheral blood and tissue T-cell receptor expression was determined at baseline and after injury. Results: At baseline, we found significant differences in the expression of CD4, CD8, and L selectin between peripheral blood T cells and tissue T cells, After trauma, the percentage of tissue T cells expressing CD8 decreased from 19 +/- 9 to 14 +/- 5 (p < 0.05) and the percentage expressing gamma delta-TcR receptors decreased from 12 +/- 4 to 7 +/- 2 (p < 0.05), T-cell phenotype composition in peripheral blood was not affected by trauma. Conclusion: Peripheral blood T-cell composition differs from tissue T-cell composition before and after trauma. Trauma produced changes in tissue T-cell phenotypes but not in peripheral blood T-cell phenotypes.