© 2006 The Japanese Biochemical Society.
Regular Paper |
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
1 Department of Immunology and Microbiology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu 061-0293 and 2 Division of Radio Isotope and Biosafety Research, National Research Institute for Child Health and Development, Taishido, Setagaya-ku, Tokyo 154-8567
* To whom correspondence should be addressed at the present address: Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, Sanuki, Kagawa 769-2193. Tel: +81-87-894-5111, Fax: +81-87-894-0181, E-mail: tamotok{at}kph.bunri-u.ac.jp
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 Mg2+-dependent and Ca2+/Mg2+-independent groups. Interestingly, two proteins in the Mg2+-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, Mg2+-dependent proteins including CR3 but not Ca2+/Mg2+-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.