Lymphocyte activation after non-thermal trauma

Background: Severe injury causes immunological changes that may contribute to a poor outcome. Longitudinal characterization of lymphocyte response pat terns may provide further insight into the basis of these immunological alt erations. Methods: Venous blood obtained seven times over 2 weeks from 61 patients wi th injury severity scores above 20 was assessed for lymphocyte phenotypic a nd activation markers together with serum levels of interleukin (IL) 2 , IL -4, soluble IL-2 receptor (sIL-2R), soluble CD4 (sCD4), soluble CD8 (sCD8) and interferon gamma. Results: Severe injury was associated with profound changes in the phenotyp ic and activation profile of circulating lymphocytes. Activation was indica ted by increased numbers of T cells expressing CD25, CD69 and CD71, and rai sed serum levels of IL-2, sIL-2R, sCD4 and sCD8. Relatively higher levels o f sIL-2R and sCD4 were found in patients with sepsis syndrome. Conclusion: Polytrauma is associated with dramatic alterations in the pheno typic and activation profile of circulating lymphocytes which are generally independent of clinical course. In contrast, several lymphocyte soluble fa ctors, including sCD4 and sIL-2R, paralleled the clinical course. These dat a provide new insight into lymphocyte responses after injury and suggest th at further assessment of soluble factors as clinical correlates, including those related to lymphocyte activation or generalized inflammation, may be warranted.