Severity, time, and beta-adrenergic receptor involvement in surgery-induced immune alterations

Although investigations of surgical stress in animals have reported immune alterations, surprisingly little is knows about the variables or mechanisms contributing to the effect. Thus, we completed a series of experiments inv estigating the immune-altering effects of surgery severity, time of maximal immune alterations, and recovery, as well as the involvement of P-adrenerg ic receptors in surgery-induced immune alterations in Lewis rats. Immune al terations included natural killer (NK) cell cytotoxicity as well as B- and T-cell proliferation. Results showed increased im mune suppression with lar ger incisions (6 cm > 3 cm > anesthesia > saline). In addition, maximal imm une alterations induced by surgery occurred after 24 h; anesthesia effects predominated at the earlier time points, Recovery of immune status varied d epending on the immunological measure of interest, Although Mt cell cytotox icity returned to control values within 2 days, B cell proliferation remain ed suppressed for at least 8 days, and T-cell proliferation did not begin t o recover until 4-8 days following the surgical procedure. To assess the me chanisms involved in surgery-induced immune alterations, follow-up assessme nts evaluated the effect of nadolol, a beta-adrenergic receptor antagonist, on surgery-induced immune alterations. Results show that nadolol blocks th e surgery-induced reduction in B- and T-cell proliferation but has no effec t on the suppression of NK cell cytotoxicity. These results indicate the ne ed to consider surgical severity and postoperative time of immune assessmen t when investigating the immune-altering effects of surgery. Importantly, a ctivation of beta-adrenergic receptors appears to play a modulatory role in surgery-induced immune alterations, (C) 1998 Academic Press.