Increase of serum interleukin 2 receptor level in thermally injured patients

Serum concentrations of receptor for the T cell growth factor interleukin 2 (IL-2R) were compared to the capacity of activated T cells to express surface IL-2R in patients with major burns. In immunosuppressed patients the numbers of cells expressing IL-2R were transiently (survivors) or permanently (nonsurvivors) reduced (up to 50 and 90%, respectively). In contrast, the levels of soluble IL-2R in patients' sera were significantly (P < 0.001-0.05) elevated throughout the postburn period. Within 24 hr postinjury, over 90% of patients demonstrated 400-3500 U/ml of serum IL-2R compared with 120-340 U/ml in normal controls. Soluble IL-2R, when patients became immunosuppressed, further increased to 4445 ± 962 U/ml in nonsurvivors and to 2031 ± 578 U/ml in survivors, and demonstrated a significant capacity to inhibit the activity of exogenous IL-2. In survivors the levels of serum IL-2R declined at discharge, to 1009 ± 104 U/ml. Thus, in thermally injured patients, soluble IL-2 receptor concentrations are elevated, and could interfere with IL-2-mediated immune interactions.