Capture of heat-killed Mycobacterium bovis bacillus Calmette-Guérin by intelectin-1 deposited on cell surfaces.
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 Ca(2+)-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.
Tsuji
Shoutaro
S
Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431, USA. stsuji@gancen.asahi.yokohama.jp
Yamashita
Makiko
M
Hoffman
Donald R
DR
Nishiyama
Akihito
A
Shinohara
Tsutomu
T
Ohtsu
Takashi
T
Shibata
Yoshimi
Y
D000595:Amino Acid Sequence; D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D058851:GPI-Linked Proteins; D006801:Humans; D037102:Lectins / Q000276:immunology*; D016676:Macrophages, Alveolar / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009163:Mycobacterium bovis / Q000378:metabolism*; D010587:Phagocytosis / Q000276:immunology*; D020836:Protein Structure, Quaternary; D011817:Rabbits
D001500:BCG Vaccine; D016207:Cytokines; D058851:GPI-Linked Proteins; C432397:ITLN1 protein, human; C115657:Itlnb protein, mouse; D037102:Lectins