Biological activities of human mannose-binding lectin bound to two different ligand sugar structures, Lewis A and Lewis B antigens and high-mannose type oligosaccharides.
The biological activities of mannose-binding lectin (MBL) which binds to different ligands on mammalian cells were examined using two types of Colo205 cells, a human colon adenocarcinoma cell line: one naturally expressing Lewis A and Lewis B antigens as ligands for MBL (NT-Colo205), and the other modified to express high-mannose type oligosaccharides by treatment with benzyl-2-acetamide-2-deoxy-alpha-galactopyranoside and 1-deoxymannojirimycin (Bz+dMM-Colo205). Although the final lysis was not observed, the deposition of C4 and C3 was observed on both types of Colo205 cells after treatment with MBL and complements as a result of complement activation by MBL. MBL bound to Bz+dMM-Colo205 could also activate human peripheral blood leukocytes and induce superoxide production; however, MBL bound to NT-Colo205 could not. This may be explained by the lower affinity of MBL to Lewis A and Lewis B antigens than to high-mannose type oligosaccharides under physiological conditions, since MBL bound to NT-Colo205 was more easily released from the cell surface than that bound to Bz+dMM-Colo205 at 37 degrees C. These findings suggest that the difference in the affinity of MBL to its ligands could influence the expression of some biological activities of MBL.
Muto
S
S
Department of Clinical Chemistry, School of Pharmaceutical Sciences, Toho University, Miyama 2-2-1, Funabashi, 274-8510, Chiba, Japan. satoshi@phar.toho-u.ac.jp
Takada
T
T
Matsumoto
K
K
D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D002352:Carrier Proteins / Q000378:metabolism*; D037222:Collectins; D003167:Complement Activation / Q000502:physiology; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007962:Leukocytes / Q000502:physiology; D007983:Lewis Blood Group Antigens / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism*; D013696:Temperature; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D037222:Collectins; D007983:Lewis Blood Group Antigens; D009844:Oligosaccharides; C404741:galactopyranosyl-1-3-galactopyranosyl-1-3(4)-N-acetylglucosamine; D008358:Mannose