Developmental expression of 97A6 antigen of CD34⁺ PB cells in the presence of IL-3. MACS-selected CD34⁺ PB cells from normal PB were cultured in serum-free medium in the presence of 100 ng/mL IL-3 (n = 3) and analyzed for 97A6 antigen expression at different stages of culture. Percentages of 97A6-positive cells are plotted against days of culture. 10,000 cells of each sample were analyzed on a FACSCalibur flow cytometer, and percentage positive cells was calculated with the Cellquest software.