Suppression of leukemic but not normal donor BFU-E and CFU-GM growth by leukemia-reactive CTL line 3. CTL line 3 was irradiated (10 Gy) and incubated for 4 hours with bone marrow MNC from donor HS or patient KG at various effector:target ratios. After 4 hours, the cells were resuspended in methylcellulose as a single-cell suspension and cultured in the presence of multiple hematopoietic growth factors. Progenitor cell growth is expressed as the percentage of BFU-E or CFU-GM growth in the absence of CTL. All metaphases from MNC of patient KG were t(9;22) positive.