Three-color flow cytometry analysis of postnatal CD34⁺ CD1⁻ thymocytes. CD34⁺CD1⁻ thymocytes isolated as described in the Materials and Methods were analyzed by flow cytometry for the correlated expression of CD44, CD34, and one of the indicated MoAbs. Electronic gates were set as shown in the upper biparametric plot to analyze the expression of CD2, CD5, CD38, CD7, CD33, CD13, HLA-DR, and CD45RA antigens on CD44^brightCD34^bright(unshaded areas) and CD44^intCD34^int (shaded areas) thymocytes. Background values (dashed histograms) were determined with isotype-matched irrelevant antibodies.