Analysis of CTL-mediated inhibition of colony formation of CD34⁺ cell populations purified from patients with leukemia and normal donors.

(A) CTL-mediated inhibition of colony formation by purified CD34⁺ cells cocultured for 4 hours with CTL at an effector/target cell ratio of 10:1. Untreated control CD34⁺cells were cultured under the same conditions without CTL. CTL treated and untreated control cells were then plated in methylcellulose, and after 14 days the numbers of granulocyte macrophage colony-forming units (GM-CFU) were counted. Shown is the percentage of GM-CFU after CTL treatment using the GM-CFU observed in the untreated controls as 100% reference. This figure shows the mean and standard deviation of independent experiments with CD34⁺ cells from 9 HLA-A0201⁺ patients with CML and 7 normal donors and with CD34⁺ cells from 5 HLA-A0201⁻ patients with CML. (B) Colony formation by A0201⁺/CD34⁺CML cells that were untreated or treated for 4 hours with high-avidity P126-specific CTL (line 81) or with low-avidity CTL (line 85) before plating. Shown are GM-CFU and BFU-E using the number of colonies observed in the untreated controls as 100% reference.