Intercellular adhesion molecules, type I transmembrane glycoproteins, with immunoglobulin-like C2-type domains that are the ligands for leucocyte function antigen-1 (LFA-1; CD11a/CD18: a β2-integrin) and to a lesser extent Mac-1 (CD11b/CD18). ICAM-1 (CD54, 532 aa) is expressed on the luminal surface of endothelial cells and various haematopoietic cells and is up-regulated on activated T and B cells. It is an important ligand for leucocyte adhesion, the site to which rhinovirus binds and to which Plasmodium falciparum-infected erythrocytes adhere. ICAM-2 (CD102, 275 aa) is constitutively expressed on endothelium and on resting lymphocytes and monocytes and is not up-regulated by inflammatory cytokines. ICAM-3 (CD50, 547 aa) plays a role in the early stages of the immune response and crosslinking of ICAM-3 induces an rise in intracellular calcium and activates tyrosine kinases. ICAM-4 (CD242, formerly LW blood group antigen, 271 aa) is an erythrocyte-specific adhesion ligand that also binds to the monocyte/macrophage-specific CD11c/CD18. ICAM-5 (telencephalin, 924 aa) is only expressed in the forebrain and seems to play a role in neuronal targeting.
Subjects: Medicine and Health.