(a) weak Strong binding Aflinity constant 101 I05 06 10 108 19 Io-10 10-17 (mol/L》 Tcell receptors Adhesion Molecules Growth Factor Receptors Antibodies (b) TH cell Antigen-presenting cell TC cell Target cell Peptide CD2 -.03001FA3 Antigen CD2 0000-1FA3 LFA-I ICAM-1 LFA-1 000 ICAM-I 00 0 Peptide 0 0 TCR- TCR- cass 000 Class I MHC CD3 CD3 MHC CD 0 CD8 C000 CD45R 酒 00 CD22 CDi5R 0u0 CD22 CD28 1XO B7 D