Expression of CD20 on normal B cells promotes deletion of CD20-specific cTCR⁺ T cells. (A-B) Thy1.1⁺Leu16⁺ polyclonal effector T cells (10⁷) were injected intravenously into Thy1.2⁺ WT or hCD20 mice. Spleens were obtained 7 days later and analyzed for donor T cells and endogenous B cells (B). Numbers under boxes in panel A represent the percentage of Thy1.1⁺ T cells of blood CD4 or CD8 T cells. (C-D) WT mice were injected with 10⁷ Thy1.1⁺Leu16⁺CD8⁺ T cells. Twenty-four hours later, the mice were challenged with 2 × 10⁷ WT or hCD20 splenocytes. (C) Three days later blood was analyzed for donor Thy1.1⁺ T cells. (D) Spleens were obtained 7 days after challenge and analyzed for donor T cells. Bar graphs represent mean ± SE. Data are representative of 2 experiments with 3 mice per group. P values were obtained with t tests.