CD34⁺ CB cells were cultured in SF medium supplemented with KFT3 in the absence or presence of TNF (20 ng/mL). After 5 days a neutralizing Ab against TNF was added at 2 μg/mL to the groups indicated and cultured for another 3 days, at which time the EEs of 100 000 CD34⁺CB cells were transplanted into irradiated NOD-SCID mice. Human engraftment was investigated after 6 weeks. Data are presented as number of mice positive for human reconstitution with both B and myeloid cells. Also shown is the percentage human engraftment (representing total human reconstitution independent of whether both myeloid and B cells were observed) of individual animals within each group.