Intercellular adhesion molecule 1

Intercellular adhesion molecule 1 (ICAM-1) is a cell adhesion molecule that mediates leukocyte recruitment and trans-endothelial migration by functioning as a ligand receptor for integrins LFA-1 and MAC-1 on lymphocytes and neutrophils (UniProt: P05362). It also serves as a receptor for certain viral pathogens including rhinovirus and coxsackievirus. The protein operates at the interface between immune cells and endothelial barriers, where it regulates cell–cell contact strength in proportion to antigen stimulation.

ICAM-1 is expressed on endothelial and epithelial cells and plays a central role in inflammatory leukocyte trafficking. It interacts with the cytoskeletal regulator ARHGEF26 to organize apical cup structures during transendothelial migration (UniProt: P05362). The molecule is also subject to viral antagonism, including degradation by Kaposi's sarcoma-associated herpesvirus E3 ubiquitin ligase.

In Alzheimer's disease, ICAM-1 is upregulated in post-mortem brain tissue relative to age-matched controls (Chaparral AD proteomics). The protein showed an average log2 fold-change of 1.49 across two subcellular fractions in TMT-labeled mass spectrometry analysis of human post-mortem AD brain, suggesting enhanced leukocyte adhesion and neuroinflammatory activity in the disease state.