Fig 8.11 Crosslinking of CD28 dellvers the co-stimulatory signal CTLA-4 binds B7(CD80 or CD86)more avidly than does during activation of naive T cells and induces the expression of CTLA-4(CD152) CD28 and delivers inhibitory signals to activated T cells naive T cell activated T oell 6 台68686 CD28 T-Cell recepto CD4 LN CTLA-4 (CD152 B7 Antigen MHC class antigen-presenting cell antigen-presenting cell