Flow cytometric analysis of CD34 and HLA-DR antigen expression on LD and CD34⁺ cells purified from human cord blood. The vertical axis indicates the relative number of cells on a linear scale, and the horizontal axis indicates fluorescence on a logarithmic scale. (A) and (B) CD34 antigen expression and (C) and (D) HLA-DR antigen expression on LD mononuclear cells or purified CD34⁺ cells, respectively. Cells were incubated either with antihuman FITC-conjugated anti-HLA-DR MoAb or PE-conjugated anti-CD34 MoAb (━) or with negative control antibodies (─).