Complement receptor type 3 plays an important role in development of protective immunity to primary and secondary Corynebacterium pseudotuberculosis infection in mice

The present study was performed to investigate the role of CR3, the type 3 complement receptor, in host defense against primary and secondary Coryneba cterium (C.) pseudotuberculosis infection in mice. Treatment of mice with 5 C6, an anti-CR3 monoclonal antibody (mAb), resulted in unrestricted multipl ication of bacteria in the organs and dramatically increased mortalities of the infected mice. Histological examinations showed the inflammation, dege neration and necrosis of organs and revealed that the infection-enhancing e ffect of 5C6 mAb was associated with the failure of mice to focus mononucle ar phagocytes at sites of bacterial multiplication. These results suggest t hat CR3 plays an important role in host defense against primary as well as secondary C, pseudotuberculosis infection in mice.