Antibiotics modulate vaccine-induced humoral immune response

The effects of antibiotics on the antigen-specific humoral immune response are not known. Macrolides, tetracyclines, and beta-lactams are commonly pre scribed antibiotics. The first two are. known to have immunomodulatory acti vities. The effects of clarithromycin, doxycycline, and ampicillin on the p rimary and secondary antibody responses to tetanus toroid, a pneumococcal p olysaccharide vaccine, a hepatitis B virus surface antigen (HBsAg) vaccine, and lire attenuated Salmonella typhi (Ty21a) were investigated using a mou se model. For the mice receiving the tetanus toroid, the immunoglobulin M ( IgM) level of the clarithromycin group at day 7 was significantly lower tha n the corresponding antibody level of the normal saline (NS) group. Far the mice receiving the pneumococcal polysaccharide vaccine, the total antibody and IgM levels of the clarithromycin group and the IgM level of the doxycy cline group at day 7 were significantly lower than the corresponding antibo dy levels of the ampicillin and NS groups. For the mice receiving the HBsAg vaccine, the IgM level of the doxcycline group at day 7 was significantly lower than the corresponding antibody levels of the clarithromycin and NS g roups, while the IgM level of the clarithromycin group at day 28 was signif icantly lower than the corresponding antibody levels of the doxycycline, am picillin, and NS groups. For the mice receiving all three vaccines, there w ere no statistically significant differences between any of the antibody le vels of the ampicillin group and the corresponding antibody levels of the N S group. For the mice receiving Ty21a, the total antibody levels of the amp icillin group at days 7 and 21 were significantly higher than the correspon ding antibody levels of the NS group. Moreover, the IgM levels of the clari thromycin, doxycycline, and ampicillin groups at days 7 and 21 were signifi cantly higher than the corresponding antibody levels of the NS group. Furth ermore, the total antibody level of the ampicillin group at day 21 was sign ificantly higher than the corresponding antibody level of the doxycycline g roup. For all four vaccines, there were no statistically significant differ ences among the serum levels of interleukin-10 and gamma interferon for the mice treated with the various antibiotics. We conclude that clarithromycin and doxycycline, but not ampicillin, suppress the antibody responses of mi ce to T-cell-dependent and T-cell-independent antigens, whereas all three a ntibiotics enhance the antibody response to live attenuated mucosal bacteri al vaccines.