(A and B) Dual-parameter immunofluorescence analysis demonstrating the expression of CD34 and 103B2/9E10 (A) or 105.A5 (B) epitopes by BMMNCs. SBA-depleted BMMNCs were stained with the directly conjugated MoAb HPCA-2-PE (-CD34) and 103B2/9E10 (detected with anti-IgG₃-FITC). Data are displayed as dual-parameter histograms of 5 × 10⁴ light-scatter-gated events collected as list-mode data. Stat-markers were established with the use of nonbinding, isotype-matched control antibodies as described in Materials and Methods. (C and D) Assay of clonogenic progenitors in populations sorted on the basis of CD34 and MoAb 103B2/9E10 (C) or 105.A5 (D). FACS of the CD34⁺, CD34⁺103B2/9E10⁺, and CD34⁺103B2/9E10^lo/− or CD34⁺105.A5⁺, and CD34⁺105.A5^lo/− subpopulations demonstrates that clonogenic progenitors ([▪] CFU-GM, [□] BFU-E, and [▧] CFU-Mix) are present almost exclusively in the CD34⁺103B2/9E10⁺ (C) and CD34⁺105.A5⁺ (D) subpopulation. Results are expressed as the number of CFU-GM at day 14 per 1 × 10³cells plated. Data represent the mean ± SE (n = 3).