Intercellular adhesion molecule-1 (ICAM-1) in cellular immune reactions in the human central nervous system.

Cryostat sections of human central nervous system (CNS) tissue samples from 10 cases of multiple sclerosis (MS), 11 cases with inflammation and necrosis, and 24 normal controls were immunostained with antibodies to intercellular adhesion molecule-1 (ICAM-1) and its integrin ligand lymphocyte function-associated molecule-1 (LFA-1). In 18 controls, small numbers of CNS microvessels were ICAM-1-positive. There were more numerous ICAM-1-positive vessels in active MS plaque edges, viral encephalitis lesions, infarcts, and in six controls. Within active MS plaques and in viral infections, mononuclear cells and some glia also were ICAM-1-positive. Mononuclear but not CNS resident cells were LFA-1-positive. Thus, CNS vessel ICAM-1 expression is variable in amount in postmortem samples of normal human CNS tissue, may increase early and focally in cellular immune reactions, and, via binding of LFA-1, may promote leukocyte influx into the CNS. Intercellular adhesion molecule-1 expression on parenchymal cells may indicate additional interactions with LFA-1 on inflammatory cells in diverse CNS lesions.