Monoclonal antibody MEM-166 recognizes the CD177 antigen, a 58-64kDa glycosyl-phosphatidylinositol (GPI) anchored plasma membrane glycoprotein that is also expressed on secondary granules. CD177 is also known as neutrophil-specific antigen NB1 and human neutrophil antigen HNA-2a. CD177 is expressed on neutrophils and neutrophilic metamyelocytes, and myelocytes from 89 to 97 per cent of healthy individuals. The expression of CD177 is upregulated on granulocytes stimulated with the chemotactic peptide For-Met-Leu-Phe-OH. The function of CD177 is under investigation, and there is evidence that CD177 is a heterophilic binding partner of platelet endothelial cell adhesion molecule-1 PECAM-1 (CD31). This interaction may constitute a pathway involved in neutrophil transmigration. CD177 is unique in that it is expressed on subpopulations of neutrophils, altogether on approximately 60% of neutrophils. Application: IHC (f), FACS, Immunoprecipitation, Western Blot