To determine how well leukemia cells directly stimulate alloreactive T cells, irradiated B6 beta-2-microglobulin-deficient (β2M−/−) mice were reconstituted with B6 β2M−/− BM, wt H60+ BC-CML, and B6 TMH60. Here, B2M is linked to chronic myelogenous leukemia, BCR-ABL1 positive.