Multilineage differentiation of BCNU/O6BG-selected MGMT P140K–expressing long-term hematopoiesis. FACS analysis of peripheral blood cells from unselected control mice and mice that received a transplant of 4 × 105 cells before (4 weeks after transplantation) and after repetitive monthly injections of 5 μg/g BCNU and 20 μg/g O6BG (8, 12, 16, 20, 24, 28, and 32 weeks after transplantation, indicated by successive bars) was performed 23 to 25 days after each cycle of BCNU/O6BG treatment. The GFP+ hematopoiesis contributed to erythroid (TER119), monocytic (MAC1), granulocytic (GR1), B-lymphoid (B220), and T-lymphoid (CD3) lineages in unselected control animals as well as in BCNU/O6BG-treated mice even after serial transplantation. In primary recipient mice (A), the marked hematopoiesis produced fewer erythroid cells and monocytic cells accompanied by a relative increase in the proportion of the transduced T lymphocytes (*P < .01). In secondary recipients (B), no difference in the lineage contribution of the transduced hematopoiesis was observed with or without BCNU/O6BG treatment (n = 10). An increase in the proportion of marked T-lymphoid cells was detected again after tertiary transplantation in BCNU/O6BG-treated recipients (n = 11, *P < .05), whereas all other cell lineages remained unaffected (C). Standard error of the mean (± SEM) is shown for 11 to 12 individual mice per bar.
