T-cell subpopulations following thermal injury.

In this report, we have enumerated T-cell subsets as defined by receptors for immunoglobulin isotypes at 24 to 48 hours postburn. T cells possessing surface receptors for the Fc fragment of IgM represent a population of cells with helper activity, T mu cells, and T cells possessing surface receptors for the Fc fragment of IgG represent a population of cells with suppressor-cytotoxic function, T gamma cells. Significant alterations in the number and proportion of regulatory T cells was observed early in the course of severe burn trauma. A decrease in total T cells was accompanied by a drop in IgM-Fc binding lymphocytes, helper cells, in all burns greater than 20 per cent total body surface area. An increase in IgG-Fc binding lymphocytes was observed only in those patients who had sustained the most severe injuries, greater than 60 per cent total body surface area burn or greater than 25 per cent third-degree burn. These changes correlated linearly with the amount of full thickness injury, and the ratio of T mu:T gamma cells was significant at 24 to 48 hours postburn in predicting the risk of septic death.