CB-derived CD4⁺CD25⁺ T cells are deficient with regard to their regulatory function harboring a subset with limited net suppressive effects.

<p>(<b>A</b>) Specificity of proliferation to BLG and BLG+LPS is displayed via CFSE labeling experiments. (<b>B</b>) Inhibition experiments were performed using and increasing amount of MACS-sorted CD4⁺CD25⁺ T cells to the CD4⁺CD25⁻ fraction in presence of irradiated APCs. The inhibitory potential is expressed as relative proliferation compared to the CD4⁺CD25⁻ cells. Graphs indicate the means of 5–8 independent experiments with means +/− SEM. Wilcoxon sign rank test was applied. P-values of less than 0.05 were considered significant. (<b>C</b>) CBMCs were separated via FACS on day 0 according to their CD25 and CD127 expression. Four subgroups (CD4⁺CD25^highCD127^low (F1), CD4⁺CD25^intermediateCD127^low (F2), CD4⁺CD25^intermediateCD127^high (F3), and CD4⁺CD25⁻ T cells (CD25⁻)) were obtained. An inhibition assay was performed with the first three fractions using the CD4⁺CD25⁻ T cells as effector cells. The inhibitory potential is expressed as relative proliferation compared to the CD4⁺CD25⁻ subgroup. Graphs indicate the means of 4 independent experiments and SEM. (<b>D</b>) Real-time PCR analysis was performed to analyze the FOXP3, TGF-β, and IL-10 expression for further examination of the four fractions. Data represents three independent experiments showing the normalized expression of means +/− SEM.