Figure 7.

MDM2, p21, and Bim are differentially regulated between plate-bound Ab-stimulated CD4⁺CD25⁻ and CD4⁺CD25⁺ T cells. A, Expression of p53, MDM2b, and p21 by CD4⁺CD25⁻ and CD4⁺CD25⁺ T cells after plate-bound or bead-bound anti-CD3 and anti-CD28 Ab stimulation. After 3 d of activation, total cell lysate from the indicated cells was prepared and subjected to SDS-PAGE (0.75 × 10⁶ cells/lane), followed by Western blotting and immunodetection of the indicated molecules. The specificity of the p53 band was confirmed by Western blotting of lysates from p53^−/− T cells (data not shown). B, The indicated cells types were stimulated with plate- or bead-bound Abs; after 3 d, total cell lysate was analyzed for Bim by Western blotting, as in A. The lower panel shows the expression of the constitutively expressed protein HSC70. C, CD4⁺CD25⁻ T cells from WT, p21^−/−, and Bim^−/− mice were stimulated by plate-bound anti-CD3 and anti-CD28 Abs for 5 d and analyzed for Annexin V and 7-AAD staining.