(a) weak →Strong binding Affinity constant 104 0-5 106 107 18 10r9 1o-10 10-17 (molL) Tcell receptors Adhesion Molecules Growth Factor Receptors Antibodies (b) TH cell Antigen-presenting cell TC cell Target cell Peptide 0000-1FA3 CD2 LFA3 Antigen CD2 LFA-1- ICAM-1 LFA-1~ 00 00 Peptide 00 0 TCR- TCR- 000 Class I MHC 00 ,.ass目 CD3 CD3 MHC t CDI CD8 CO C000 CD45R C1D22 CD15R 0 232效 CD22 CD28 00 B7 D