Characterization of the IL-15 niche in primary and secondary lymphoid organs in vivo

Abstract

Significance IL-15 is a cytokine critical for development and maintenance of T lymphoid cells. However, the identity and distribution of IL-15–expressing cells in lymphoid organs are not well understood. The present study reveals, by using IL-15–CFP knock-in mice that IL-15 was expressed in subsets of thymic epithelial cells, bone marrow stromal cells, lymph node stromal cells, and blood endothelial cells, a unique perspective of IL-15 niche in immune microenvironment. Taken together with our previous observation on IL-7–producing cells, this study suggests that some stromal cells express IL-7 and IL-15 differentially. Thus, the immune microenvironment appears to be consisted of functionally distinct subsets of stromal cells, expressing different cytokines.