LFA-1 and Mac-1,two β2 integrin members constitutively expressed on neutrophils (PMNs),mediate PMN recruitment via binding to their same ligand of intercellular cell adhesive molecule-1 (ICAM-1).The slow rolling and firm adhesion of PMNs rely on LFA-1 while the cell crawling is dependent on Mac-1,in which their distinct functions are hypothesized to be governed by their different binding capacities.Here we first applied an adhesion frequency approach to compare their kinetics in the quiescent and activated states using three different molecular species.