Lymphocyte activation after non-thermal trauma

Abstract

Background: Severe injury causes immunological changes that may contribute to a poor outcome. Longitudinal characterization of lymphocyte response patterns may provide further insight into the basis of these immunological alterations. Methods: Venous blood obtained seven times over 2 weeks from 61 patients with injury severity scores above 20 was assessed for lymphocyte phenotypic and 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 γ. Results: Severe injury was associated with profound changes in the phenotypic and activation profile of circulating lymphocytes. Activation was indicated by increased numbers of T cells expressing CD25, CD69 and CD71, and raised serum levels of IL-2, sIL-2R, sCD4 and sCD8. Relatively higher levels of sIL-2R and sCD4 were found in patients with sepsis syndrome. Conclusion: Polytrauma is associated with dramatic alterations in the phenotypic and activation profile of circulating lymphocytes which are generally independent of clinical course. In contrast, several lymphocyte soluble factors, including sCD4 and sIL-2R, paralleled the clinical course. These data provide new insight into lymphocyte responses after injury and suggest that further assessment of soluble factors as clinical correlates, including those related to lymphocyte activation or generalized inflammation, may be warranted.