Glycobiology Advance Access originally published online on January 29, 2009
Glycobiology 2009 19(5):518-526; doi:10.1093/glycob/cwp013
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Capture of heat-killed Mycobacterium bovis bacillus Calmette-Guérin by intelectin-1 deposited on cell surfaces
2 Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA
3 Division of Cancer Therapy, Kanagawa Cancer Center Research Institute, Kanagawa 241-0815, Japan
4 Pathology and Laboratory Medicine, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
1 To whom correspondence should be addressed: Tel: +81-45-391-5761, ext. 4054; Fax: +81-45-366-3157; e-mail: stsuji{at}gancen.asahi.yokohama.jp
Received on November 12, 2008; revised on January 25, 2009; accepted on January 27, 2009
Intelectin is an extracellular animal lectin found in chordata. Although human and mouse intelectin-1 recognize galactofuranosyl residues included in cell walls of various microorganisms, the physiological function of mammalian intelectin had been unclear. In this study, we found that human intelectin-1 was a serum protein and bound to Mycobacterium bovis bacillus Calmette-Guérin (BCG). Human intelectin-1-binding to BCG was inhibited by Ca2+-depletion, galactofuranosyl disaccharide, ribose, or xylose, and was dependent on the trimeric structure of human intelectin-1. Although monomeric, mouse intelectin-1 bound to BCG, with its C-terminal region contributing to efficient binding. Human intelectin-1-transfected cells not only secreted intelectin-1 into culture supernatant but also expressed intelectin-1 on the cell surface. The cell surface intelectin-1 was not a glycosylphosphatidylinositol-anchored membrane protein. Intelectin-1-transfected cells captured BCG more than untransfected cells, and the BCG adherence was inhibited by an inhibitory saccharide of intelectin-1. Intelectin-1-preincubated cells took up BCG more than untreated cells, but the adhesion of intelectin-1-bound BCG was the same as that of untreated BCG. Mouse macrophages phagocytosed BCG more efficiently in medium containing mouse intelectin-1 than in control medium. These results indicate that intelectin is a host defense lectin that assists phagocytic clearance of microorganisms.
Key words: galactofuranose / innate immunity / intelectin / lectin / mycobacteria