Addition of noradrenaline to intrathecal morphine augments the postoperative suppression of natural killer cell activity.

PURPOSE: Intrathecal administration of morphine has been shown to suppress natural killer (NK) cell activity. We tested the hypothesis that combined administration of morphine and noradrenaline would further modify NK cell activity in patients undergoing hysterectomy.

METHODS

Thirty female patients were randomly divided into three groups of ten patients each. Groups MN and M received intrathecal morphine (0.5 mg) dissolved in 5 ml of physiological saline with and without 5 micro g noradrenaline, respectively. Group C received saline alone. After the intrathecal administration, general anesthesia was induced. Blood samples were withdrawn before and 2 h after surgery and on postoperative days 1, 2, and 7 to determine the NK cell activity, the ratio of T-helper/inducer cells (CD4) to T-suppressor/cytotoxic cells (CD8), the levels of interleukin-6 (IL-6) and interleukin-8 (IL-8), and the plasma concentrations of catecholamines and cortisol.

RESULTS

NK cell activity decreased on postoperative day 1 in groups MN (12.0 +/- 2.7%) and M (25.4 +/- 9.6%) compared with their respective baseline levels. In group MN, NK cell activity remained lower (23.7 +/- 8.0%) on postoperative day 2 than the baseline value before surgery.

CONCLUSION

Intrathecal administration of morphine causes a decrease in NK cell activity, and its combined use with noradrenaline prolongs the suppression of NK cell activity.