TGF-β secretion in mononuclear cells and CD25 and Foxp3 expression in CD4+ T-cells of cord blood (CB) and peripheral blood (PB). (A) Contour plots of CD4 and CD25 expression in unstimulated CB and PB T-cells. Representative examples of one out of 114 CB and 79 PB samples analyzed are shown, illustrating the separation of the CD25- and CD25+ populations in CB CD4+ cells as compared to a broader range CD25 expression in PB CD4+ cells. (B) Production of TGF-β cytokines by CB (n = 49) and PB (n = 59) mononuclear cells (MNCs) measured by ELISA in supernatants 4 days after incubation in media (unstimulated) and phytohemagglutinin (PHA). The median is represented by the horizontal bar within the box. The upper and lower boundaries of the box represent the 25th to 75th percentiles of the data, respectively. Observations < 1.5 times the height of the box beyond either quartile are displayed within the whiskers. (C) Intracellular expression of Foxp3 in unstimulated samples of CB and PB MNCs analyzed by flow cytometry. The CD4+ cells were gated and analyzed for expression of CD25 and FOXP3. The percentage of CD4+ cells expressing CD25 and FOXP3 is shown in the upper right-hand quadrants. FOXP3 are not distinctly expressed within the CD4+CD25+bright cell population in CB as compared to PB. Compared to CB, maternal PB had a significant population of CD25+FOXP3- cells (upper left-hand quadrants). Results are representative examples of one out of 63 CB and 78 PB samples analyzed.