Phenotype of NOD/SCID engrafting T-ALL cells. ALL cells were sorted for expression of CD34 and CD4 (n = 7; A) or CD34 and CD7 (n = 5; B). Both unsorted cells and the sorted subfractions were evaluated for their ability to engraft irradiated NOD/SCID recipients. Each patient is represented by a specific symbol, and each symbol depicts the engraftment obtained as measured by CD45⁺ cells present in the bone marrow of the NOD/SCID recipients.