ITGB2 encodes the β2 integrin subunit (CD18), a critical component of leukocyte adhesion molecules essential for immune cell function and tissue infiltration. ITGB2 forms heterodimeric complexes with multiple α-subunits (ITGAL, ITGAM, ITGAX, ITGAD) to serve as receptors for intercellular adhesion molecules (ICAM-1, ICAM-2, ICAM-3) and other ligands including complement fragment iC3b and fibrinogen. These integrin complexes mediate leukocyte adhesion to endothelial cells and facilitate transmigration of neutrophils, T cells, and other immune cells 123. ITGB2 signaling activates JAK/STAT and PI3K/AKT pathways to regulate immune cell activation, natural killer cell cytotoxicity, and macrophage function 45. Pathologically, ITGB2 mutations cause leukocyte adhesion deficiency type 1 (LAD-I), characterized by severe immunodeficiency and recurrent infections 6. Beyond immune function, ITGB2 expression is dysregulated in multiple diseases including diabetic nephropathy, autoimmune disorders (SLE/Sjögren's syndrome), and cancers where it promotes tumor-associated macrophage infiltration and metabolic reprogramming 7895. Gene therapy restoring ITGB2 expression in LAD-I patients demonstrates clinical efficacy, with 100% HSCT-free survival and dramatic reduction in infection-related hospitalizations 6.