Antigen-specific cell contacts in the immune system are strengthened by antigen-nonspecific interactions, mediated in part by lymphocyte-function associated (LFA) antigens. Recently, ICAM-1 (intercellular adhesion molecule-1) has been defined as a ligand for LFA-1. Monoclonal antibodies to ICAM-1 block T lymphocyte adhesion to fibroblasts and endothelial cells and disrupt the interaction between cytotoxic T cells and target cells. ICAM-1 is found on leukocytes, fibroblasts, epithelial cells and endothelial cells and its expression is regulated by inflammatory cytokines. The normal function of human ICAM-1 is to provide adhesion between endothelial cells and leukocytes after injury or stress. However, ICAM-1 is also used as a receptor by the major group of human rhinoviruses and is a catalyst for the subsequent viral uncoating during cell entry. Monoclonal antibodies recognize a 95 kDa cell surface glycoprotein the major human rhinovirus receptor, ICAM-1
