Regulation of CD8+ Memory T‐Cell Differentiation by B Cells

Studies in B‐cell‐deficient mice have indicated that B cells might play an important role in regulating CD8+ T cell responses. The interpretation of experiments in B‐cell‐deficient mice is complicated due to the abnormal histological architecture of lymphoid organs. Additionally, the role of antigen‐specific B cells in regulation of CD8+ T cell responses has not been studied. The B‐cell transgenic mice (HEL‐ITg), in which all B cells express the antigen receptor for hen egg lysozyme, is an excellent model to study the role of antigen‐specific B cells in regulating CD8+ T cell responses without the complication of lymphoid abnormalities associated with B cell knockout mice. In response to an acute infection with lymphocytic choriomeningitis virus (LCMV), HEL‐ITg mice mounted a potent primary CD8+ T‐cell response. However, the functional and phenotypic maturation of memory CD8+ T cell was adversely affected in HEL‐ITg mice. LCMV‐specific memory CD8+ T cells were impaired in IL‐2 production and exhibited a predominantly CD62L lo /CD127 lo phenotype. Additionally, memory CD8+ T cells in HEL‐ITg mice provided poor protective immunity to secondary challenge. These studies show that antigenic‐specific B cells are essential for optimal CD8 T cell responses to an acute viral infection. Work was supported by a PHS grant to M. Suresh from NIH.