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

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Abstract
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‐2Kb‐restricted ovalbumin peptide OVA257 – 264 made memory CD8+ CD44high T cell responses to OVA257 – 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‐2bxd mice with OVA257 – 264‐pulsed minor‐incompatible H‐2b or H‐2d 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.