Lymphocyte function-associated antigen 1–Intercellular adhesion molecule 1 complex (LFA-1–ICAM-1)

The Lymphocyte function-associated antigen 1–Intercellular adhesion molecule 1 (LFA-1–ICAM-1) complex is a fundamental molecular interaction that occurs at the immune synapse, the specialized junction between a lymphocyte and an antigen-presenting cell [4]. LFA-1 is an integrin heterodimer composed of the alpha-L (CD11a) and beta-2 (CD18) subunits, while ICAM-1 (CD54) is a member of the immunoglobulin superfamily [1, 2, 3]. This complex facilitates firm leukocyte adhesion to the vascular endothelium and provides critical co-stimulatory signals necessary for T-cell activation and proliferation [4]. In various inflammatory and autoimmune diseases, such as psoriasis and dry eye disease, the LFA-1–ICAM-1 axis is overactive, leading to excessive T-cell recruitment and tissue damage [6]. Therapeutic agents like lifitegrast are designed to competitively inhibit this interaction, effectively reducing inflammation in conditions like keratoconjunctivitis sicca [5]. Historically, the monoclonal antibody efalizumab targeted this complex for psoriasis treatment but was withdrawn due to the risk of progressive multifocal leukoencephalopathy [6]. Beyond inflammation, the complex is involved in cancer metastasis, where it aids the extravasation of tumor cells into distant organs. Understanding the structural dynamics of this complex remains vital for developing targeted therapies that balance efficacy with the risk of systemic immunosuppression. Sources: [1] UniProt P20333; [2] UniProt P05106; [3] UniProt P05362; [4] PMID: 25324123; [5] FDA Drugs@FDA; [6] PMID: 12815136.

Other names

CD11a/CD18–CD54 complexIntegrin alpha-L beta-2–ICAM-1 complexLFA-1–ICAM-1 interactionImmune synapse adhesion complex

Competitive inhibition of the LFA-1 I-domain binding to the ICAM-1 D1 domain, blocking leukocyte adhesion and co-stimulation [4, 5].