B Cells Promote CD8 T Cell Primary and Memory Responses to Vaccines

The close relationship between B cells and CD4 T cells has been carefully studied, revealing a collaborative effort, where B cells promote the activation, differentiation, and expansion of CD4 T cells, while the so-called “helper” cells provide signals to B cells, influencing their class-switching and fate. Interactions between B cells and CD8 T cells are not as well studied, although CD8 T cells do exhibit an accelerated contraction after certain infections in B cell-deficient mice. Here, we found that B cells significantly enhance primary CD8 T cell responses following vaccination. Moreover, memory CD8 numbers and function are impaired in B cell-deficient animals, leading to increased susceptibility to bacterial challenge. We also found that IL-27 production by B cells contributes to their impact on primary, but not memory CD8 responses. Better understanding of the interactions between CD8 T cells and B cells may aid in the design of more effective future vaccine strategies.