Adhesion molecules and leukocyte trafficking receptors on T cells and other leukocytes

Adhesion molecules and leukocyte trafficking receptors are a diverse group of cell surface proteins, including integrins, selectins, and chemokine receptors, that mediate the recruitment of immune cells from the blood into tissues (Ley et al., 2007, Nature Reviews Immunology). This process follows a well-defined adhesion cascade involving rolling, activation, firm adhesion, and transmigration across the vascular endothelium (StatPearls, 2023). In chronic inflammatory and autoimmune diseases, such as multiple sclerosis and Crohn's disease, these pathways are often pathologically upregulated, leading to excessive leukocyte infiltration and tissue destruction (Mitroulis et al., 2015, Current Pharmaceutical Design). Therapeutic strategies focus on blocking these interactions using monoclonal antibodies or small molecules to prevent the entry of pathogenic cells into specific organs (Zundler et al., 2017, Gut). For example, natalizumab targets the alpha4-integrin to treat multiple sclerosis, while vedolizumab targets the alpha4beta7-integrin specifically for inflammatory bowel disease (FDA, 2020). While these therapies are highly effective, they carry significant safety risks, most notably the potential for opportunistic infections like progressive multifocal leukoencephalopathy (PML) due to impaired local immune surveillance (Tysabri Prescribing Information). Consequently, modern drug development aims to identify organ-specific trafficking signals to improve the safety profile of these immunomodulators.

Other names

Cell adhesion moleculesCAMsLeukocyte homing receptorsIntegrinsSelectinsChemokine receptorsLeukocyte-endothelial adhesion molecules

These molecules function as a coordinated system to facilitate leukocyte extravasation; drugs targeting them act as antagonists that disrupt the binding between leukocyte receptors (e.g., alpha4beta1, alpha4beta7, LFA-1) and their endothelial ligands (e.g., VCAM-1, MAdCAM-1, ICAM-1) or inhibit chemokine-mediated signaling (e.g., CCR5, CXCR4), thereby preventing the accumulation of inflammatory cells in target tissues (Ley et al., 2007; Zundler et al., 2017).