CD25+CD4+ regulatory T cells suppress T cell activation and regulate multiple immune reactions in in vitro and in vivo studies. To define the regulatory function of human CD25+ CD4+ T cells at various stages of maturity, we investigated in detail the functional differences of CD25+ CD4+ T cells from thymocytes, cord blood (CB), and adult peripheral blood (APB). CB CD25+ CD4+ T cells displayed low-FOXP3 protein expression level and had no suppressive activity. In contrast, CD25+ CD4+ T cells from thymocytes or APB expressed high expression level of FOXP3 protein associated with significant suppressive activity. Although CB CD25+ CD4+ T cells exhibited no suppressive activity, striking suppressive activity was observed following expansion in culture associated with increased FOXP3 expression and a shift from the CD45RA+ to the CD45RA− phenotype. These functional differences in CD25+ CD4+ T cells from Thy, CB, and APB hence suggest a pathway of maturation for Treg in the peripheral immune system.
Fujimaki, W., Takahashi, N., Ohnuma, K., Nagatsu, M., Kurosawa, H., Yoshida, S., … Morimoto, C. (2008). Comparative study of regulatory T cell function of human CD25+ CD4+ T cells from thymocytes, cord blood, and adult peripheral blood. Clinical and Developmental Immunology, 2008. https://doi.org/10.1155/2008/305859