Changes in the levels of serum-soluble interleukin-2 receptor after surgical stress.

Purpose: Surgical stress induces alterations in numerous physiological functions, including the cell-mediated immune response. It is known that interleukin-2 receptor (IL-2R) is released from its specific affinity membrane receptor on activated T lymphocytes and then is detected as a form of the alpha-chain of the IL-2R in the bloodstream. The levels of serum-soluble IL-2R (sIL-2R) reflect the quantity of activated T lymphocytes. This study investigated the changes in the serum sIL-2R levels and the relationship of such changes with other cytokines and the number of lymphocytes after abdominal surgery.

Methods: Twenty-four patients who were scheduled to undergo abdominal operations were enrolled in this study. Blood samples of these cases were collected before surgery, and on postoperative days (POD) 1, 3, 7, and 14. The levels of serum sIL-2R were measured by an enzyme-linked immunosorbent assay.

Results: The levels of serum sIL-2R achieved the maximal values on POD 1, and gradually decreased until POD 14. The levels of serum sIL-2R on POD 1, 3, and 7 were significantly higher than the preoperative levels. There was a significant and positive correlation between the levels of serum sIL-2R and serum IL-6. There were significant and positive correlations between the levels of sIL-2R and the number of white blood cells and neutrophils. Conversely, there was a significantly negative correlation between the levels of serum sIL-2R and the number of lymphocytes.

Conclusions: As high levels of serum sIL-2R were recognized after abdominal operations, the proliferation of T lymphocytes might still be highly activated in a state of surgical stress, though it is popularly acceptable that surgical stress induces a suppression of cell-mediated immunity.