Reversal of postoperative immunosuppression in man by vitamin A

The effects of therapy with vitamin A on immune responsiveness after extensive surgical treatment were studied in vitro. Postoperatively, in control patients, there was depression of the total lymphocyte count and the response in the mixed lymphocyte reaction to a pool of stimulating cells. Treatment with pharmacologic dosages of vitamin A prevented depression of these parameters in the postoperative period. The mitogenic response to phytohemagglutinin and monocyte mediated hemolysis was not consistently altered by operation in control patients, but there was a trend toward increased activity in those receiving vitamin A. Thus, vitamin A appears to be an immunostimulant in man.