B7-2 regulates survival, phenotype, and function of APCs

The absence of B7-2-mediated costimulation protects NOD mice from the development of diabetes. Although the effects of B7-2 on T cell priming are well known, its impact on the function of APCs is not fully elucidated. We tested APC function and survival in mice lacking B7-2. A significant reduction in the phagocytic ability was observed in both splenic and pancreatic lymph node-associated dendritic cells (DCs) in B7-2 knockout (KO) mice. DCs from B7-2KO mice exhibited enhanced susceptibility to death, which was reflected by their reduced total cell numbers. Phenotypic analysis of APCs in B7-2KO mice revealed a significantly decreased proportion of CD8α ⁺CD205⁺ DCs. Interestingly, an enhanced proportion of B7-H1⁺ and B7-DC⁺ DCs were observed in B7-2KO mice. Lastly, we found that B7-2 deficiency significantly diminished the PKC-ε response in APCs upon CD28-Ig stimulation. In conclusion our data suggests that B7-2 promotes the generation of a mature APC repertoire and promotes APC function and survival.