Sex differences in immune responses to cephalothin in guinea pigs

Guinea pigs of two strains, outbred Hartley and inbred Strain 2, were immunized subcutaneously with cephalothin (CET, 20 mg/body) alone, without adjuvant. Immune responses to the antibiotic were assessed by guinea-pig passive cutaneous anaphylaxis (GP-PCA) and active systemic anaphylaxis (GP-ASA) reactions. The immune response to CET in the female Hartley guinea pigs was higher than that in the males. In contrast, no difference in response to CET in Strain 2 guinea pigs was observed between males and females. These results suggested that female Hartley guinea pigs possessing a higher response should be employed in antigenicity studies involving the beta-lactam antibiotics.