Induction of CD40, CD80, and CD86 on CD34⁺blood cells in alloMLC. Three-color staining with CD34PerCP, CD40FITC, and CD80PE or CD86PE MoAbs was performed on CD34⁺ blood cells immediately after separation (top row, 0 hrs) and after 1 day of culture with allogeneic mononuclear cells at 1:2 ratio (bottom row, 24 hrs alloMLC). Cells that fluoresced brightly for anti-CD34 MoAb were gated for analysis. The proportion of CD34⁺ cells expressing CD40 and/or CD80 or CD86 is shown in the appropriate quadrant of each figure.