Analysis of Fc receptors for IgG on guinea pig peritoneal macrophages by the use of a monoclonal antibody to one of the Fc receptors.
The variety and properties of Fc receptors (FcR's) for homologous IgG on guinea pig peritoneal macrophages were investigated with the use of a mouse monoclonal antibody, VIA2 IgG1, prepared by fusion of splenic cells of a mouse immunized with guinea pig macrophages with a mouse myeloma cell line. VIA2 IgG1 completely inhibited the formation of macrophage rosettes with IgG1 antibody-sensitized erythrocytes, but not that with IgG2 antibody-sensitized erythrocytes. The Fab' of VIA2 IgG1 also completely inhibited the bindings of both monomeric and ovalbumin-bound IgG1 antibodies to macrophages. On the other hand, the Fab' did not affect the binding of monomeric IgG2 antibody to macrophages, although it partially inhibited that of ovalbumin-bound IgG2 antibody. These results show that at least two distinct types of FcR are present on guinea pig macrophages; one (FcR1,2) binds monomeric IgG1 antibody and also antigen-bound IgG1 and IgG2 antibodies, and the other (FcR2) binds monomeric and antigen-bound IgG2 antibodies alone, and also that VIA2 IgG1 binds specifically to FcR1,2. When FcR1,2 was isolated by affinity chromatography on F(ab')2 of VIA2 IgG1 coupled to Sepharose, it gave a main band with a molecular weight of 55,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which was indistinguishable from the main band isolated with the IgG1 immune complex. The number of FcR1,2 per macrophage cell was estimated to be 2 X 10(5) by measuring the binding of 125I-Fab' of VIA2 IgG1.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis*; D000915:Antibody Affinity; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D006168:Guinea Pigs; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D008297:Male; D010529:Peritoneal Cavity; D011817:Rabbits; D011961:Receptors, Fc / Q000276:immunology* / Q000378:metabolism; D017452:Receptors, IgG; D012397:Rosette Formation
D000911:Antibodies, Monoclonal; D011961:Receptors, Fc; D017452:Receptors, IgG