Background: Leukocyte β2 integrins of LFA-1, Mac-1, and αxβ2 are constituted with the same β2 subunit and highly homologous α subunits respectively.They mediate leukocyte-endothelial cell adhesion in inflammation by binding of their Ⅰ domains presenting on the top of each α subunit to the common ligand of ICAM-1.The three members involve in distinct stages of inflammation cascade even they have similar structures and the same ligand.Their distinct functions implicate structural difference, while the corresponding structural profile remains unclear.