ABSTRACT
BACKGROUND: T-cell response to trauma has been assessed primarily by sampling peripheral blood lymphocytes. We hypothesized that lymphocytes residing in tissue and traveling through lymph vessels are more likely to be activated by tissue injury and hemorrhage-induced hypoperfusion. We compared peripheral blood T-cell response with tissue or lymph T-cell response in an ovine model of multiple injury. METHODS: Anesthetized adult sheep instrumented with a chronic prefemoral lymph fistula were subjected to lower-extremity fractures, fixed-volume hemorrhage, resuscitation, and fracture stabilization. Peripheral blood and tissue T-cell receptor expression was determined at baseline and after injury. RESULTS: At baseline, we found significant differences in the expression of CD4, CD8, and L selectin between peripheral blood T cells and tissue T cells. After trauma, the percentage of tissue T cells expressing CD8 decreased from 19 +/- 9 to 14 +/- 5 (p < 0.05) and the percentage expressing gammadelta-TcR receptors decreased from 12 +/- 4 to 7 +/- 2 (p < 0.05). T-cell phenotype composition in peripheral blood was not affected by trauma. CONCLUSION: Peripheral blood T-cell composition differs from tissue T-cell composition before and after trauma. Trauma produced changes in tissue T-cell phenotypes but not in peripheral blood T-cell phenotypes.
Subject(s)
CD4-Positive T-Lymphocytes/metabolism , CD8-Positive T-Lymphocytes/metabolism , Femoral Fractures/metabolism , L-Selectin/metabolism , Multiple Trauma/metabolism , Shock, Hemorrhagic/metabolism , Animals , Female , Femoral Fractures/blood , Femoral Fractures/complications , Flow Cytometry , L-Selectin/blood , Multiple Trauma/blood , Multiple Trauma/complications , Sheep , Shock, Hemorrhagic/blood , Shock, Hemorrhagic/complicationsABSTRACT
OBJECTIVE: Intravenous fat infusions are a standard component of total parenteral nutrition (TPN). We studied the effects of withholding fat infusions in trauma patients requiring TPN. DESIGN: Polytrauma patients receiving TPN were randomized to receive a standard fat emulsion dose (L) or to have fat infusions withheld (NL) for the first 10 days of TPN. The two groups received the same amino acid and carbohydrate dose (isonitrogenous, nonisocaloric). MATERIALS AND METHODS: Clinical outcome parameters were measured. T-cell function was assessed by measuring lymphokine activated killer and natural killer cell activity. MEASUREMENTS AND MAIN RESULTS: Demographics including Injury Severity Score (27 +/- 8; 30 +/- 9) and APACHE II scores (23 +/- 6; 22 +/- 5) were similar for the L (n = 30) and NL (n = 27) groups, respectively. Differences (p < 0.05) were found in length of hospitalization (L = 39 +/- 24; NL = 27 +/- 16), intensive care unit length of stay (L = 29 +/- 22; NL = 18 +/- 12), and days on mechanical ventilation (L = 27 +/- 21; NL = 15 +/- 12). The L group had a higher number of infections (72 in 30) than the NL group (39 in 27) and T-cell function was depressed in this group. CONCLUSIONS: Intravenous fat emulsion infusions during the early postinjury period increased susceptibility to infection, prolonged pulmonary failure, and delayed recovery in critically injured patients. It is not clear whether the improved outcome in the NL group was directly related to withholding the fat infusions or due to the hypocaloric nutritional regimen (underfeeding) these patients received.