T-cell stimulatory capacity of CBDC. (A) Graded doses of lin⁻- (CD3, CD11b, CD14, CD16, CD19, CD34, CD56, and glycophorin A negative) enriched CB cells were cocultured with 10⁵ allogeneic CB T cells and after 5 days, BrdU uptake was determined (▪). Results are presented as mean ± SD of triplicates. Background BrdU uptake of lin⁻-enriched cells (□) and T cells (○) alone are shown. Statistical significance (**P < .01 and *P < .05) is indicated. (B) For the minimal number of lin⁻ enriched stimulator cells (total, 2,557 ± 2,077; n = 11), which stimulated a significant response, the cell numbers of the lin⁻/HLA-DR⁺ (266 ± 107; n = 10), lin⁻/HLA-DR⁻ (1,362 ± 1,476; n = 10), lin⁺/HLA-DR⁺ (192 ± 210; n = 9), and lin⁺/HLA-DR⁻(991 ± 1,168; n = 9) subpopulations, composing the lin⁻-enriched cells, are shown. The numbers of CD14⁺ monocytes (1,627 ± 642; n = 5) required for significant stimulation are indicated for comparison.