Immunosuppression follows systemic T lymphocyte activation in the burn patient.

A general consensus that thermal injury affects T lymphocyte function adversely is supported particularly by the observation that burned patients' lymphocytes secrete reduced levels of biologically active IL-2 in vitro. In the same patients, however, high serum concentrations of the low-affinity IL-2 receptor (IL2R alpha), a product of an IL-2-activated gene, have been observed. In this study a significant proportion of patients also demonstrated over-physiological levels (from 2 to 500 U/ml) of serum IL-2 ascertained by immunoassay. Increases in serum IL-2 content correlated significantly (P less than 0.02) with those of serum IL-2R alpha during the first week post-burn. Later, serum IL-2R alpha levels continued to increase up to 30 days while IL-2 eventually declined. Thus, augmented secretion of IL-2R alpha appears related to the high serum IL-2 content. Therefore refractoriness to further immune stimulation may be due to early activation of the lymphoid system, rather than to an intrinsic incapacity of T lymphocytes for generating sequential responses.