Human CD8+CXCR3+ T cells have the same function as murine CD8+CD122+ Treg.

The importance of CD8(+)CD122(+) Treg in the maintenance of immune homeostasis has been previously demonstrated in mice. Because the expression pattern of CD8 and CD122 in humans is different from that in mice, human CD8(+) Treg that correspond to the murine CD8(+)CD122(+) Treg have not been identified. In this study, we performed DNA microarray analyses to compare the gene expression profiles of CD8(+)CD122(+) cells and CD8(+)CD122(-) cells in mice and found that CXCR3 was preferentially expressed in CD8(+)CD122(+) cells. When we analyzed the expression of CD122 and CXCR3 in murine CD8(+) cells, we observed a definite population of CD122(+)CXCR3(+) cells. CD8(+)CXCR3(+) cells in mice showed similar regulatory activities to CD8(+)CD122(+) cells by in vivo and in vitro assays. While CD8(+)CD122(+)CXCR3(+) cells are present in mice, CD8(+)CXCR3(+) cells, but not CD8(+)CD122(+) cells, are present in humans. In the in vitro assay, human CD8(+)CXCR3(+) cells showed the regulatory activity of producing IL-10 and suppressing IFN-gamma production from CD8(+)CXCR3(-) cells. These results suggest that human CD8(+)CXCR3(+) T cells are the counterparts of murine CD8(+)CD122(+) Treg.