INTERCELLULAR-ADHESION MOLECULE-2 (CD102) BINDS TO THE LEUKOCYTE INTEGRIN CD11B CD18 THROUGH THE A-DOMAIN/

The interactions between the leukocyte-specific beta 2-integrins clust er of differentiation (CD) Ag CD11/CD18 and their ligands, the interce llular adhesion molecules (ICAMs), play important roles in many adhesi on-dependent leukocyte functions. ICAM-1 is known to be a ligand for b oth CD11a/CD18 and CD11b/CD18. ICAM-2, whose two extracellular Ig doma ins show the highest homology to the two NH2-terminal domains of ICAM- 1, has been previously shown to be a ligand for CD11a/CD18. We recentl y found that a 22-amino acid CD11a/CD18-binding peptide, P1, derived f rom the first domain of ICAM-2, also binds to purified CD11b/CD18. In the present study, we demonstrate that the ICAM-2 protein interacts wi th CD11b/CD18, and the binding is through the CD11b A domain.