[Analysis of CD4(+)CD25(+)CD127(low/-) Treg cells in mice]

The quantitative identification and enrichment of viable regulatory T cells (Treg) requires reliable surface markers that are selectively expressed on Treg. Foxp3 is the accepted marker of natural Treg, but it cannot be used to isolate cells for functional studies. CD127 is a new surface marker expressed in Treg cells. In this study, two populations of Treg, including CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+)T cells, and profiles of the Foxp3 expression in CD4(+)CD25(+)CD127(low/-) cells were compared to evaluate which population is better. The peripheral blood cells were collected and spleen suspension of BALB/C mice were prepared, and using triple staining CD4, CD25, CD127 and CD4, CD25, Foxp3. The profiles of Treg, including CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+) were detected by flow cytometry. The quadruple staining CD4, CD25, Foxp3 and CD127 were used to determine the CD127 expression in CD4(+)CD25(+)Foxp3(+) cells. The results showed that on T cell subset the median expression levels of CD4(+), CD4(+)CD25(+) were 39.02%, 5.35% in peripheral blood and 23.49%, 3.86% in spleen. On CD4(+) T cell subset, the median expression level of CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+)T cells were 7.13%, 3.97% in peripheral blood and 12.8%, 8.23% in spleen. The ratio of CD4(+)CD25(+)CD127(low/-) T cells was higher than that of CD4(+)CD25(+)Foxp3(+) cells in both peripheral blood and spleen cells (P < 0.01). The CD4(+)CD25(+)CD127(low/-) cells highly expressed Foxp3, while the CD4(+)CD25(+)Foxp3(+)T cells lowly expressed CD127. It is concluded that compared with the CD4(+)CD25(+)Foxp3(+) populations, CD4(+)CD25(+)CD127(low/-) T cells better fit the definition of naturally occurring regulatory T cells in peripheral blood cells and spleen of BALB/C mice. CD127(low/-) is a characteristic marker on surface of CD4(+)CD25(+) Treg cells, and has been confirmed to be more specific marker for quantitatively sorting Treg cells.