Peptide-pulsed splenic dendritic cells prime long-lasting CD8(+) T cell memory in the absence of cross-priming by host APC.

Immunization with cells expressing endogenous antigens can stimulate long-lived CD8(+) T cell memory. In many cases, the response is also stimulated by host antigen-presenting cells (APC) that have processed antigen from internalized apoptotic cells or cell fragments. This study investigated whether immunization with peptide-pulsed dendritic cells (DC) could prime long-lasting, peptide-specific CD8(+) T cell immunity in the absence of cross-priming by host APC. C57BL / 6 female mice immunized with syngeneic male splenic DC pulsed with the H-2K(b)-restricted ovalbumin peptide OVA(257 - 264) made memory CD8(+) CD44(high) T cell responses to OVA(257 - 264) and the male antigen HY more than 1 year after immunization. Establishment and maintenance of peptide-specific CD8(+) T cell memory did not require antibody or B cells. Immunization of H-2(bxd) mice with OVA(257 - 264)-pulsed minor-incompatible H-2(b) or H-2(d) DC demonstrated that CD8(+) T cells were primed exclusively by the injected cells, and not by peptide transferred to host APC, even though there was very effective cross-priming for CD8(+) T cell responses to the minor antigens expressed by the DC. Thus peptide-pulsed DC can prime long-lasting CD8(+) memory responses without any requirement for cross-priming by other APC.