Suppression of lymphocyte responses by cephalosporins

Human peripheral blood lymphocytes were cultured in several concentrations of each of several cephalosporins. Responses to phytohemagglutinin were compared with that of duplicate cultures containing penicillin-streptomycin, chloramphenicol, or no antibiotics. Possible effects of cephalosporins on responses of lymphocytes to concanavalin A and pokeweed mitogen were similarly determined. Significant suppression of responses to phytohemagglutinin and concanavalin A were seen in cultures containing 50 microgram each of cephalothin, cephalexin, or cephradine per ml. Lymphocyte responses to pokeweed mitogen were suppressed by 50 microgram of cephalexin, cephradine, or cefoxitin per ml. A higher concentration (100 microgram/ml) of all cephalosporins except cefoxitin and cefazolin suppressed the phytohemagglutinin response to less than 20% that of controls. Chloramphenicol (50 microgram/ml) did not inhibit the response to any mitogen used. These findings suggest that cephalosporins should not be used for prevention of bacterial overgrowth in certain cell cultures. Since many of the cephalosporins were suppressive in therapeutically attainable concentrations, these results may have potential clinical significance.