This pilot project will examine the hypothesis that severe injury adversely influences antigen-specific T helper cell activity, with subsequent increases in the susceptibility of injured patients to develop severe infections and/or systemic inflammatory response syndrome (SIRS). The PI will determine whether the pattern of cytokine production changes after severe injury within a given individual, correlate the cytokine profiles observed with in vivo recall antigen-specific skin tests, & correlate immunologic profiles with clinical course.