Defect of CD8⁺ Memory T Cells Developed in Absence of IL-12 Priming for Secondary Expansion

Abstract

IL-12 priming plays an important role in stimulation of CD8⁺ effector T cells and development of CD8⁺ memory T (Tm) cells. However, the functional alteration of CD8⁺ Tm cells developed in the absence of IL-12 priming is elusive. In this study, we investigated the capacity of secondary expansion of CD8⁺ Tm cells developed from transgenic OT I CD8⁺ T cells. The latter cells were in vitro and in vivo stimulated by ovalbumin (OVA)-pulsed dendritic cells [DC_OVA and (IL-12^−/−)DC_OVA] derived from wild-type C57BL/6 and IL-12 gene knockout mice, respectively. We demonstrated that IL-12 priming is important not only in CD8⁺ T cell clonal expansion, but also in generation of CD8⁺ Tm cells with the capacity of secondary expansion upon antigen re-encounter. However, IL-12 signaling is not involved in CD8⁺ Tm cell survival and recall responses. Therefore, this study provides useful information for vaccine design and development.