Immunization with dendritic cells pulsed ex vivo with recombinant chlamydial protease-like activity factor induces protective immunity against genital Chlamydia muridarum challenge

We have shown that immunization with soluble recombinant (r) chlamydial protease-like activity factor (rCPAF) and a T helper (Th) 1 type adjuvant can induce significantly enhanced bacterial clearance and protection against Chlamydia–induced pathological sequelae in the genital tract. In this study, we investigated the use of bone marrow derived dendritic cells (BMDCs) pulsed ex vivo with rCPAF+CpG in an adoptive subcutaneous immunization for the ability to induce protective immunity against genital chlamydial infection. We found that BMDCs pulsed with rCPAF+CpG efficiently up-regulated the expression of activation markers CD86, CD80, CD40 and major histocompatibility complex class II (MHC II), and secreted interleukin-12, but not IL-10 and IL-4. Mice adoptively immunized with rCPAF+CpG-pulsed BMDCs or UV-EB+CpG-pulsed BMDCs produced elevated levels of antigen-specific IFN- and enhanced IgG1 and IgG2a antibodies. Moreover, mice immunized with rCPAF+CpG-pulsed BMDCs or UV-EB+CpG-pulsed BMDCs exhibited significantly reduced genital Chlamydia shedding, accelerated resolution of infection, and reduced oviduct pathology when compared to infected mock-immunized animals. These results suggest that adoptive subcutaneous immunization with ex vivo rCPAF-pulsed BMDCs is an effective approach, comparable to that induced by UV-EB-BMDCs, for inducing robust anti-Chlamydia immunity.