Fig. 1.

CD11c+ DCs but not B cells are the APCs that prime naïve CD8 T cells ex vivo. Two days after cutaneous immunization with OVA-expressing lentivector, DCs and B cells were sorted (A) and utilized for stimulating OT-I cell proliferation ex vivo (B). Only the CD11c+ DCs were found to be able to stimulate naïve CD8 T cell proliferation although B cells were also found to express transgene. The induction of in vivo CTL activity was also unaffected in B cell knockout mice (C), further indicating that B cells did not play a measurable role in priming naïve CD8 T cell responses.