Survival from diagnosis to death from leukemia of 19 T-cell lineage ALL patients. ( — ) Patients whose leukemic cell populations engrafted in SCID mice; (- - -) patients for whom there was no engraftment. Patients currently alive and patients who died of causes other than leukemia are indicated by tick marks on the respective curves. Survival is significantly different between the 2 groups (P < .01, log-rank test).