Abstract
Rat mast cell granules and plasma membrane fractions were obtained from highly purified intact cells by homogenization followed by Percoll and sucrose density gradient centrifugation respectively and immunostained with two types of mouse monoclonal anti-MAG antibodies: IgG antibody recognizing a polypeptide moiety of intact MAG (IgG-P) and IgM antibody recognizing a carbohydrate moiety (IgM-C) . Both intact cells and granule fraction, but not plasma membrane fraction were well stained with IgM-C.
Granule fraction fixed with glutaraldehyde showed a ring-like pattern by immunostaining with IgM-C. On the contrary, neither intact cells nor granules and plasma membrane fractions were reacted with IgG-P. Both intact cells and granule fraction treated with chloroform-methanol were also densely stained with IgM-C., indicating that IgM-C positive epitope is present in the granule fraction of the mast cell and shares with a carbohydrate moiety of MAG.
