Modification of antibody response to type III pneumopolysaccharide by route of injection of pertussis vaccine.

Pertussis vaccine (PV) or diphtheria toxoid-PV-tetanus toxoid (DPT) altered the antibody response of BALB/c female mice to type III pneumococcal polysaccharide antigen (S3). The key factor affecting the magnitude of the response to S3 was the route of injection of PV or DPT, whereas the route of injection of S3 was not crucial. Subcutaneous injections of DPT augmented the antibody response to low, optimal, and tolerogenic (high) doses of S3 injected either subcutaneously or intraperitoneally. This enhancement was persistent and was observed both when S3 and DPT were mixed and injected subcutaneously and when S3 and DPT were injected concurrently at separate subcutaneous sites. When either PV or DPT was injected intraperitoneally, the antibody response to subcutaneously or intraperitoneally injected S3 was significantly decreased. These experiments demonstrate a dichotomy of effect dependent on the route of administration of PV. Most studies in mice utilizing PV employ the intraperitoneal injection route, and it is important to consider whether PV treatment by this route may have unique effects. Our data suggest that intraperitoneal injection of PV suppresses B cells, possibly by influencing regulatory cell function.