αLβ2

αLβ2 integrin (LFA-1; CD11a/CD18) is a leukocyte-restricted β2 integrin formed by the association of the αL (ITGAL) and β2 (ITGB2) subunits, and it functions as a central mediator of leukocyte intercellular adhesion and immune cell communication^[1]. Through binding to intercellular adhesion molecules (ICAM-1, ICAM-2, and ICAM-3), αLβ2 regulates leukocyte arrest, transendothelial migration, and lymphocyte costimulatory signaling during immune responses^[1][7]. Mechanistically, αLβ2 activity is controlled by coordinated inside-out and outside-in signaling that modulates integrin affinity and avidity, thereby linking extracellular ligand recognition to intracellular signaling pathways governing leukocyte activation and migration^[2][3]. In disease settings, impaired β2 integrin function causes leukocyte adhesion deficiency type I (LAD-I), a primary immunodeficiency characterized by defective leukocyte trafficking and recurrent infections, highlighting the essential role of αLβ2 in host defense^[4][5]. αLβ2 has also been implicated in inflammatory and autoimmune pathologies because persistent LFA-1/ICAM interactions promote leukocyte recruitment and inflammatory responses within affected tissues^[7]. Compared with related β2 integrins such as αMβ2 (Mac-1) and αXβ2 (CR4), αLβ2 is distinguished by its broad expression on leukocyte populations and its prominent role in ICAM-dependent cell-cell adhesion and immunological synapse formation^[1][6]. For experimental applications, antibodies and small-molecule inhibitors targeting the LFA-1/ICAM-1 interaction have been widely used to investigate leukocyte adhesion mechanisms and integrin-mediated immune regulation^[7].