3. Co-stimulatory molecules ()CD40 interacts with CD40L(Th cell (2)CD80(B71),CD86(B72) expressed on activated b cells ()ICAM-1, LFA-13. Co-stimulatory molecules (1)CD40 interacts with CD40L (Th cell) (2)CD80(B7.1), CD86(B7.2) expressed on activated B cells (3)ICAM-1, LFA-1