부산대학교 도서관

Background: Costimulation is a critical process in Ag-specific immune responses. Both B7.1 and CD28 molecules have been reported to stimulate T cell responses during antigen presentation. Therefore, we tested whether Ag-specific immune responses as well as protective immunity are influenced by coinjecting with B7.1 and CD28 cDNAs in a mouse HSV-2 challenge model system. Methods: ELISA was used to detect levels of antibodies, cytokines and chemokines while thymidine incorporation assay was used to evaluate T cell proliferation levels. Results: Ag-specific antibody responses were enhanced by CD28 coinjection but not by B7.1 coinjection. Furthermore, CD28 coinjection increased IgG1 production to a significant level, as compared to pgD pcDNA3, suggesting that CD28 drives Th2 type responses. In contrast, B7.1 coinjection showed the opposite, suggesting a Th1 bias. B7.1 coinjection also enhanced Ag-specific Th cell proliferative responses as well as production of Th1 type cytokines and chemokines significantly higher than pgD pcDNA3. However, CD28 coinjection decreased Ag-specific Th cell proliferative responses as well as production of Th1 types of cytokines and chemokine significantly lower than pgD pcDNA3. Only MCP-1 production was enhanced by CD28. B7.1 coimmunized animals exhibited an enhanced survival rate as well as decreased herpetic lesion formation, as compared to pgD pcDNA3. In contrast, CD28 vaccinated animals exhibited decreased survival from lethal challenge. Conclusion: This study shows that B7.1 enhances protective Th1 type cellular immunity against HSV-2 challenge while CD28 drives a more detrimental Th2 type immunity against HSV-2 challenge, supporting an opposite role of B7.1 and CD28 in Ag-specific immune responses to a Th1 vs Th2 type.