Characterization of Hyaluronan-Binding Proteins on Guinea Pig Polymorphonuclear Leukocytes: Possible Involvement of Complement Receptor Type 3 (CR3, CD11b/CD18) in the Hyaluronan–Leukocyte Interaction

Abstract

Hyaluronan (HA), a high-molecular-weight glycosaminoglycan ubiquitously present in the extracellular matrices (ECMs) of animals, plays important roles in ECM organization and cell behavior through binding to hyaluronan-binding proteins (HABPs). We previously reported that HA has anti-inflammatory effects on guinea pig phagocytes, although the nature of guinea pig HABPs was unknown. In this study, we characterized guinea pig HABPs on peritoneal polymorphonuclear leukocytes (PMNs) and blood neutrophils by flow cytometry and affinity chromatography. It was found that PMNs express diverse HABPs with different molecular weights. These HABPs maximally bound with HA over a wide pH range (6-8), and recognized HAs as small as the pentadisaccharide units of d-glucuronic acid and N-acetyl-d-glucosamine. Furthermore, they could be divided into Mg(2+)-dependent and Ca(2+)/Mg(2+)-independent groups. Interestingly, two proteins in the Mg(2+)-dependent group were found to be the two subunits of complement receptor type 3 (CR3, CD11b/CD18). Unlike PMNs, blood neutrophils expressed several functionally inactive HABPs. Among these inactive HABPs, Mg(2+)-dependent proteins including CR3 but not Ca(2+)/Mg(2+)-independent proteins were activated on phorbol ester-stimulation. These results show the existence of diverse HABPs on guinea pig neutrophils and the cell activation-dependent activation of HABPs. It is also suggested that the CR3-HA interaction is possibly involved in the regulation of neutrophil function.