Abstract
High serum level of immunoreactive but not biologically active IL-2 was detected 1 day after surgery in patients undergoing major operation (abdominal, open-heart), in proportion to the tissue injury caused by surgical trauma. IL-2 values were highest in those patients who underwent open-heart surgery and received blood transfusions. In all patients they declined in the third and fourth post-operative days. Elevated serum levels of soluble IL-2 receptors (sIL-2R) were already present 1 day after operation, and peaked in the third and fifth post-operative days after mitogen triggering. Blood lymphocytes derived from operated patients secreted reduced amounts of both IL-2 and sIL-2R compared with control lymphocytes. The extent and duration of this reduction were also proportional to the tissue trauma and were affected by blood transfusions. Based on these data we suggest that early post-operative systemic immunological activation (appearance of IL-2 in the serum) is followed by elevation of sIL-2R, which then interferes with IL-2-dependent immunity. Blood lymphocytes are probably not involved in the post-operative immunological activation. The trigger for and the site of IL-2/sIL-2R synthesis are not yet clear.