Scl is not required for Lmo2-induced thymocyte self-renewal. (A) Accumulation of immature (CD4-CD8 DN) thymocytes in Lmo2;Lck;SclΔ/– mice. Representative fluorescence-activated cell sorting analysis of total (top panel) and DN thymocytes (center and lower panels) from 2-month-old mice of the indicated genotypes. wt, wild-type; Tg, transgenic). (B) Analysis of the percentage of DN thymocytes in preleukemic mice at 6 months of age. (C) Thymic cellularity of preleukemic mice at 6 months of age. Data represent mean +SD of 3 to 5 mice per group. (D) Scl is effectively deleted in Lmo2;Lck;SclΔ/– thymocytes. Genomic DNA was extracted from the bone marrow (BM) and thymus (THY) of 6-month-old Lmo2;Lck;SclΔ/– mice and used in Southern hybridization to reveal null (–), floxed (fl), and deleted (Δ) Scl alleles. %DN indicates the percentage of DN thymocytes in the thymi analyzed. (E) Scl is not required for long-term engraftment of Lmo2-transgenic thymocytes. Thymocytes were isolated from 2-month-old mice of the indicated genotypes, and thymocytes equivalent to one-quarter of a thymus were injected into sublethally irradiated (6.5 Gy) Ly5.1 recipients. Three weeks later, the proportion of donor thymocytes was determined by flow cytometry. Points represent individual recipient mice, and unique symbols denote separate experiments. (F) Donor thymocytes from recipient mice as in (D) were gated and analyzed for CD4 and CD8 expression by flow cytometry.
