Characterization of a monoclonal antibody to guinea pig peritoneal macrophages that inhibits phagocytosis of unopsonized zymosan: structural and functional similarities of the antigen to human and mouse CR3.
A monoclonal antibody, anti-Z-1, was established by fusion of spleen cells from mice immunized with guinea pig thioglycollate-induced peritoneal macrophages (TGC-M phi s) with mouse myeloma cells, P3-X63-Ag8-6.5.3. The Fab' fragments of anti-Z-1 bound to almost all of the TGC-M phi s with a high association constant (6.0 +/- 0.8) X 10(8) M-1, and effectively inhibited phagocytic activities of the cells for unopsonized zymosan and serum-treated zymosan. On the contrary, neither the phagocytic activity for rabbit IgG antibody-sensitized sheep erythrocytes nor that for periodate-treated sheep erythrocytes was inhibited by anti-Z-1. Immunoprecipitation analysis revealed that the antigen recognized by anti-Z-1, which was named Z-1 antigen, consists of a polypeptide chain with a molecular weight of 140,000 (alpha chain) noncovalently associated with a polypeptide chain of 95,000 (beta chain). The epitope with which anti-Z-1 reacts was found to be on the alpha chain by Western blotting. Furthermore, it was found that Z-1 antigen solubilized from the cells with nonionic detergent was capable of binding to unopsonized zymosan, suggesting that Z-1 antigen may function as a receptor for zymosan. These findings show the structural and functional similarities of Z-1 molecules on guinea pig peritoneal macrophages to the third complement receptor on human and mouse leukocytes.
Tamoto
K
K
Department of Microbiology, Faculty of Pharmaceutical Sciences, Higashi-Nippon-Gakuen University, Ishikari-Tobetsu, Japan.
Tada
M
M
Hazeki
K
K
Kakinuma
T
T
Mori
Y
Y
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology*; D000918:Antibody Specificity; D000954:Antigens, Surface / Q000032:analysis*; D001666:Binding Sites, Antibody; D002462:Cell Membrane / Q000032:analysis; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D006168:Guinea Pigs; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D009895:Opsonin Proteins; D010529:Peritoneal Cavity; D010587:Phagocytosis / Q000187:drug effects*; D011951:Receptors, Complement / Q000032:analysis*; D017463:Receptors, Complement 3b; D015054:Zymosan / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D000939:Epitopes; D008565:Membrane Proteins; D009895:Opsonin Proteins; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D015054:Zymosan