To discriminate between T cell neoplasm and non-malignant causes for the increase of T cell numbers after transplantation, we analyzed the use of variable segments of the TCR beta chain (Vβ) on CD3+ T cells in the blood of healthy individuals and NSG mice that were transplanted with MNCs from AML patients (Figure 3C). Here, TRBV21-1 is linked to T-cell and NK-cell neoplasm.