ELEVATED TRANSFORMING GROWTH-FACTOR-BETA CONCENTRATION CORRELATES WITH POSTTRAUMA IMMUNOSUPPRESSION

Objective: To determine whether trauma induces an increase in the conc entration of circulating transforming growth factor-beta (TGF-beta), a nd whether there is a temporal correlation between plasma TGF-beta P c oncentration and the development of posttrauma cellular immunosuppress ion. Materials and:Methods: Male Sprague-Dawley rats were anesthetized , subjected to bilateral femur fractures or sham injury, and killed 1, 3, or 5 days later. Plasma TGF-beta levels, splenocyte phenotypes, mi togen-induced proliferation, interleukin-2 (IL-2) production, and IL-2 receptor (IL-2R) expression were determined at each time point. Measu rements and Main Results: Splenocyte proliferation increased on day 1 postinjury without corresponding change in IL-2 or plasma TGF-beta lev els, Splenocyte proliferation and IL-2 production were suppressed on d ay 3 postinjury, while plasma TGF-beta levels peaked, No differences w ere observed between trauma and control groups on day 5. Splenocyte ph enotypes and IL-2R expression were similar in injured and control rats at all times. Conclusions: Suppression of lymphocyte proliferation an d IL-2 production after trauma occurs concomitantly with a rise in pla sma TGF-beta, The immune response is restored with normalization of TG F-beta concentration, These observations suggest that TGF-beta may con tribute to posttrauma immunosuppression.