Integrin ITGAM/ITGB2 is implicated in various adhesive interactions of monocytes, macrophages and granulocytes as well as in mediating the uptake of complement-coated particles and pathogens (PubMed:9558116, PubMed:20008295). It is identical with CR-3, the receptor for the iC3b fragment of the third complement component. It probably recognizes the R-G-D peptide in C3b. Integrin ITGAM/ITGB2 is also a receptor for fibrinogen, factor X and ICAM1. It recognizes P1 and P2 peptides of fibrinogen gamma chain. Regulates neutrophil migration (PubMed:28807980). In association with beta subunit ITGB2/CD18, required for CD177-PRTN3-mediated activation of TNF primed neutrophils (PubMed:21193407). May regulate phagocytosis-induced apoptosis in extravasated neutrophils (By similarity). May play a role in mast cell development (By similarity). Required with TYROBP/DAP12 in microglia to control production of microglial superoxide ions which promote the neuronal apoptosis that occurs during brain development (By similarity). Heterodimer of an alpha and a beta subunit. ITGAM associates with ITGB2. Found in a complex with CD177 and ITGB2/CD18 (PubMed:21193407). Interacts with JAM3 (PubMed:15194813, PubMed:12208882). Interacts with THBD (PubMed:27055590). Interacts with complement factor H/CFH; this interaction mediates adhesion of neutrophils to pathogens leading to pathogen clearance. Predominantly expressed in monocytes and granulocytes (PubMed:1346576). Expressed in neutrophils (at protein level) (PubMed:21193407). The integrin I-domain (insert) is a VWFA domain. Integrins with I-domains do not undergo protease cleavage. Disease susceptibility may be associated with variants affecting the gene represented in this entry. Belongs to the integrin alpha chain family.