The in vivo effects of general and epidural anesthesia on human immune function

Impaired in vivo immunity is often observed after major surgery and is mult ifactorial. We conducted a randomized clinical study to determine the indep endent effects of general anesthesia (GA) and of lumbar epidural anesthesia (LEA) on human immune function in the absence of surgical trauma. Nineteen healthy volunteers were randomized to receive GA with thiopental and isofl urane, LEA with lidocaine, or no anesthesia (Control). Serial blood samples were tested for antibody responses to antigen inoculation, neutrophil and mononuclear cell antibody-dependent cell cytotoxicity (ADCC), natural kille r cell cytotoxicity, and neutrophil phagocytic activity. Antibody responses were similar in the three groups. Mononuclear cell ADCC increased in the L EA group at the end of the anesthetic (P < 0.05 at effector/target [E/T] ra tios of 10:1, 25:1, and 50:1). Natural killer cell cytotoxicity increased a t the end of the anesthetic in both the LEA group (P < 0.05 at all E/T rati os) and the GA group (P < 0.05 at an E/T ratio of 5:1 and 10:1). No signifi cant chan-es were observed for neutrophil ADCC or phagocytosis. General or epidural anesthesia alone, in the absence of surgery, seems to have only tr ansient and minor effects on human immune function.