Serum interleukin-2 receptor as a possible mediator of immunosuppression after burn injury

Concentrations of the interleukin-2 receptor are significantly elevated in serum after burn injury. To examine the immunoregulatory potential of this molecule, suppressive activity of sera from patients with major burns (n = 16; 40% to 80% total body surface area) was assessed before and after immunoaffinity adsorption with interleukin-2. The preadsorption level of interleukin-2 receptor in the pooled serum after burn injury was 6250 U/ml. This serum demonstrated a strong suppressive activity, inhibiting expression of cellular interleukin-2 receptor and proliferative responses of normal human lymphocytes to alloantigen and exogenous interleukin-2 by 60% to 90%. Adsorption of pooled serum after burn injury with interleukin-2 lowered the level of interleukin-2 receptor to 1800 U/ml and reduced its immunosuppressive activity. The percentage of interleukin-2 receptor-bearing cells, and cell proliferative responses, increased by 50% to 70% compared with sham adsorbed pooled serum after burn injury. Thus serum interleukin-2 receptor after burn injury may represent a specific mediator for downregulation of interleukin-2-dependent responses.