B Cells Enhance Antigen-Specific CD4 T Cell Priming and Prevent Bacteria Dissemination following Chlamydia muridarum Genital Tract Infection

B cells can contribute to acquired immunity against intracellular bacteria,but do not usually participate in primary clearance. here,we examined the endogenous cd4 t cell response to genital infection with chlamydia muridarum using mhc class-ii tetramers. chlamydia-specific cd4 t cells expanded rapidly and persisted as a stable memory pool for several months after infection. while most lymph node chlamydia-specific cd4 t cells expressed t-bet,a small percentage co-expressed foxp3,and rorγt-expressing t cells were enriched within the reproductive tract. local chlamydia-specific cd4 t cell priming was markedly reduced in mice lacking b cells,and bacteria were able to disseminate to the peritoneal cavity,initiating a cellular infiltrate and ascites. however,bacterial dissemination also coincided with elevated systemic chlamydia-specific cd4 t cell responses and resolution of primary infection. together,these data reveal heterogeneity in pathogen-specific cd4 t cell responses within the genital tract and an unexpected requirement for b cells in regulating local t cell activation and bacterial dissemination during genital infection. © 2013 li,mcsorley.