Flow cytometric comparison of CD25⁺ versus CD25^- cell lines. After 3 to 4 weeks of culture expansion, antigen expression was profiled by FACS. Shown are representative plots of CD25⁺-derived suppressor cell lines compared with CD25^--derived cell lines. Also compared are potent adult-derived cell lines. (A) CD25 and intracellular CTLA4 expression remains high on cord T suppressor line, less so for the adult-derived Ts, and largely returns to baseline for the CD25^--derived cell lines. (B) CD62L and CD27 expression remains uniformly high on cord Ts lines, on a subset of the adult lines, and diminishes on the CD25^--derived cell lines. Representative of 10 cell lines each, analyzed at 4 weeks of culture.