Thymus and T- and B-cell reconstitution. (A) Thymus reconstitution by EPLM from Flt3L-treated mice. A total of 2 × 10⁴ EPLM from C57Bl/6CD45.1 mice were injected intravenously into C57Bl/6.Rag2^–/–.Ly5.2 recipients. Three weeks after injection, the thymus contained 95% CD45.1⁺ cells (left histogram). The cytogram displays show the CD4 versus CD8 (middle panel) and CD4 versus TCR-β distribution on gated CD45.1⁺ cells. The figures in each panel indicate the percent cells in each quadrant. (B) EPLM reconstitute both T and B spleen cells. Shown are results of staining spleen cells from C57Bl/6.Rag2KO.Ly5.2 mice 7 weeks after reconstitution with 2 × 10⁴ sorted EPLM from C57Bl/6.Ly5.1 Flt3L-treated mice. The spleen contained 11.1% donor derived CD45.1⁺ cells (top histogram) and cytogram displays show the CD4 versus CD8 (top left), CD3 versus TCR-β (top right), B220 versus IgM (lower left), and CD23 versus CD21 (bottom right) distribution on gated CD45.1⁺ cells. Figures in each panel represent the percent positive cells in each quadrant. In the lower right cytogram, the regions show the 19.1% CD23⁺CD21⁺ FB and 24.5% CD23^–CD21⁺ MZB cells.