Dr Wick and colleagues add welcome data to ongoing evaluations of the immunologic effects of severe injury. Using a refined flow cytometric analysis, these investigators further define the effects of blunt trauma on the pattern and function of circulating lymphocytes: TH1 vs TH2 CD3+ cells. Prior studies have produced extremely variable results in the shift from TH1 to TH2 phenotype consistent with an increased risk for infectious and other immunologic complications.