The veto effect on the effector T cells is not affected by removal of CD34⁺ cells at the end of the cell culture.

Responder cells and irradiated allogeneic stimulator cells were cocultured for 5 days with (●) or without (○) addition of CD34⁺ cells. The responder cells were then cultured again with the original stimulators and IL-2 (10 U/mL) for 7 days. At the end of the second culture period, the responders were isolated by E-rosetting with sheep red blood cells and tested for CTL activity by analysis of ⁵¹Cr-release. A control experiment with (▴) and without (▵) addition of the same CD34 cells to an MLR of the same responder cells against a third party was carried out in parallel. Shown are the results of 1 experiment. The SD of 6 values was consistently less than 10% of the mean.