The heat stable antigen (CD24) is not required for the generation of CD4+ effector and memory T cells by dendritic cells in vivo.

Previous work has established that CD24 is a costimulatory molecule for T-cell clonal expansion. Studies using CD24 -/- mice demonstrated that CD24 plays a critical role in the CD28-independent immune response against virus and soluble antigens. The role of CD24 on dendritic cells (DCs) has not been reported. Here, we compare the CD24(+/+) and CD24(-/-) DCs in the induction of initial clonal expansion and elicitation of memory CD4(+) T cells in vivo. Our results demonstrate that the CD24 expressed on DCs is essential neither for the induction of initial T-cell clonal expansion nor for elicitation of memory activity of primed T cells in vivo.