NK cell and BL differentiation potential of CD45RA^hiCD7⁺ and CD45RA^hiLin^-CD10⁺ HPCs. Comparative analysis of CD45RA^hiLin^-CD10⁺ and CD45RA^hiCD7⁺ HPCs in limiting-dilution assay cultures under the NK condition (A) or the B condition (A). Positive wells were scored and FACS analyzed after 2 (B condition) or 3 (NK condition) weeks of culture. Upper panels show NK cell (A) and BL precursor (B) frequencies; lower panels display mean percentages + SD of CD56⁺ and CD19⁺ cells per well. Differences of CD56⁺ and CD19⁺ cell percentages in wells from CD45RA^hiLin^-CD10⁺ versus CD45RA^hiCD7⁺ HPC cultures seeded with 300 to 10 and 300 to 30 cells per well under the NK and B condition, respectively, were statistically significant (P = .01; Student t test). Results are representative of 1 experiment of 2 under each culture condition.