Impaired function of dendritic cells in alymphoplasia (aly/aly) mice for expansion of CD25+ CD4+ regulatory T cells

Alymphoplasia (aly/aly) mice are from a naturally occurring strain with a mutation in nuclear factor-kappa B inducing kinase (NIK). The NIK mutation causes disruption of the architecture of the thymus and spleen and aly/aly mice show decreased numbers of CD25(+)CD4(+)T cells in the spleen. For the expansion of CD25(+)CD4(+)T cells, interactions between dendritic cells (DCs) and CD25(+)CD4(+) regulatory T cells are necessary. We investigated the ability of DCs to induce expansion of CD25(+)CD4(+)T cells. We found that DCs are reduced in the spleen of aly/aly mice, and showed low expressions of CD80, CD86 and MHC class II molecules on the surface. DCs from aly/aly mice showed decreased ability to present ovalbumin ( OVA) to T cells from OVA specific TCR transgenic mice, and a decreased ability for alloantigen presentation. Further, DCs showed a decreased ability to induce expansion of CD25(+)CD4(+)T cells in vitro. Our results suggested that the impairment of DCs in aly/aly mice is responsible, at least in part, for the decreased numbers of CD25(+)CD4(+)T cells in the periphery of aly/aly mice.