[Regulation of perioperative immunological changes following laparotomy--effects of PSK on surgical stress].

Immune responses have been reported to decline following surgical stress, leading to an increased susceptibility to infection or to the growth of tumors. We report that preoperative treatment with PSK can inhibit the decline of immunocompetence during the perioperative period. BALB/c mice were laparotomized, and then the abdomens were closed. The concentrations of IL-6 and of IFN-gamma and IL-4 were measured. PSK treatment controlled the stress induced elevation. It was lower in the group with surgical stress than in the cultures derived from the non-treated group. The IFN-gamma concentration in the group with PSK was significantly higher than the level in the group with surgical stress alone. The IL-4 concentration was significantly lower in the surgical stress group than the control group. However, the concentration tended to be higher in the surgical stress + PSK treatment group than the group with surgical stress alone. The IFN-gamma/IL-4 ratio in the group with surgical stress was lower than the ratio in the non-treated group. The ratio in the group with PSK treatment was significantly higher than the ratio in the group with surgical stress alone. These results suggest that PSK restores the abnormality of the biological responses induced by surgical stress and corrects the reduced Th1/Th2 cytokine balance to a normal level.