Adoptive transfer of CD8α+ dendritic cells (DC) isolated from mice infected with Chlamydia muriddrum are more potent in inducing protective immunity than CD8α- DC

Chlamydial infections are serious public health concerns worldwide. In this study, we examined the role of dendritic cell (DC) subsets in inducing protective immunity against chlamydial infection using an adoptive transfer approach. We found that CD11c(+)CD8 alpha(+) (double-positive, DP) DC, compared with CD11c(+)CD8 alpha(-) (single-positive, SP) DC isolated from infected mice, are more potent inducers of protective immunity. Specifically, mice pretreated with DPDC from infected mice, upon infection with Chlamydia trachomatis mouse pneumonitis (MoPn), experienced significantly less severe body weight loss and in vivo chlamydial growth. Analysis of MoPn-driven cytokine production by immune cells revealed that mice that were treated with DPDC produced significantly higher levels of Th1 (TNF-alpha, IFN-gamma, and EL-12) but lower levels of Th2 (EL-4, EL-5, and EL-13)-related cytokines than the recipients of SPDC following infection challenge. Moreover, DPDC-treated mice displayed significantly higher levels of MoPn-specific IgG2a production and delayed-type hypersensitivity responses compared with SPDC-treated mice. Furthermore, DPDC isolated from infected mice produced higher amounts of EL-12 and IL-10 in vitro in comparison with SPDC. These data indicate that CD8 alpha(+) DC have a significantly higher capacity in inducing protective immunity compared with CD8 alpha(-) DC, demonstrating the crucial role of DC1-like cells in eliciting protection against C trachomatis infection.