ICAM1

ICAM1 Full Name

intercellular adhesion molecule 1

ICAM1 Introduction

Intercellular Adhesion Molecule-1 (ICAM-1), also known by cluster of differentiation marker CD54, is a type I transmembrane glycoprotein in the immunoglobulin superfamily that is broadly expressed at low levels on endothelial cells, leukocytes, epithelial cells and many other cell types under basal conditions. ICAM-1 contains multiple Ig-like extracellular domains that serve as binding sites for leukocyte integrins such as LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18), facilitating direct adhesive interactions between circulating immune cells and the vascular endothelium. Its expression is markedly upregulated by pro-inflammatory cytokines including TNF-α, IL-1 and interferon-γ during inflammatory responses, and the protein can also be shed into circulation as soluble ICAM-1 (sICAM-1), which is detectable in plasma and often elevated in disease states.

Figure 1. ICAM-1 intracellular signaling after integrin binding.(Sources: Haydinger CD, et al.; 2023)

Functionally, ICAM-1 plays a central role in immune surveillance, leukocyte trafficking and immune synapse formation. By binding to β2 integrins on leukocytes, ICAM-1 mediates firm adhesion of leukocytes to the endothelium and their transendothelial migration into tissues at sites of infection or injury, a key step in innate and adaptive immunity. It also contributes to antigen‑presenting cell–T‑cell interactions, enhancing immune activation through stabilization of the immunological synapse. Beyond adhesion, ICAM-1 participates in signal transduction pathways that influence cell migration, survival, and inflammatory signal amplification, and has been shown to regulate processes such as efferocytosis by macrophages during inflammation resolution.

ICAM-1 is implicated in a wide range of diseases where inflammation and immune cell recruitment are central features. Increased ICAM‑1 expression and elevated sICAM-1 levels are observed in cardiovascular diseases such as atherosclerosis, where adhesion of monocytes to vascular endothelium drives plaque formation, as well as in autoimmune and chronic inflammatory disorders including rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis and atopic dermatitis. Genetic polymorphisms in the ICAM1 gene have been associated with diabetes and diabetic nephropathy, and experimental evidence suggests roles in neuroinflammation and neurodegeneration. In cancer, ICAM-1's influence on immune cell infiltration and tumor cell adhesion contributes to complex roles in tumor progression and metastasis, making it both a biomarker and potential therapeutic target in oncology and immunomodulatory drug development.

Alternate Names for ICAM1

ICAM1; intercellular adhesion molecule 1; CD54; ICAM; ICAM-1;

• 1. Haydinger CD, et al.; Intercellular Adhesion Molecule 1: More than a Leukocyte Adhesion Molecule. Biology (Basel). 2023, 12(5):743.