1994 Volume 116 Issue 5 Pages 948-954
Three kinds of anti-GM1 monoclonal antibodies, AGM-1, -2, and -3, of the IgM class were produced by the immunization of BALB/c mice with ganglioside GM1 inserted into liposomes with Salmonella minnesota R595 lipopolysaccharides and fusion of the spleen cells with a mouse myeloma cell line. The specificities of the monoclonal antibodies obtained were elucidated through complement-dependent liposome immune lysis assay and enzyme immunostaining on thin-layer chromatograms. All of the monoclonal antibodies reacted only with ganglioside GM1, and structurally related glycosphingolipids, such as fucosyl-GM1, asialo-GM1, GM2, and GD1b, and the other gangliosides (GM3 and GD1a) tested showed no reactivity to the 3 monoclonal antibodies. These findings suggest that the monoclonal antibodies obtained may be specific for ganglioside GM1. These anti-GM1 monoclonal antibodies were used to define the expression of ganglioside GM1 on small cell lung carcinoma (SCLC) cell lines and tissues. In flow cytometric analysis and immunostaining studies, we observed that ganglioside GM1 was highly expressed on the SCLC cell lines. Results obtained with flow cytometry and immunohistochemistry agreed well with the immunochemical determination of ganglioside GM1 in lipid extracts of cell lines. Furthermore, expression of ganglioside GM1 in tumor tissues from patients with SCLC was ascertained by the immunohistochemical examination of acetone-fixed paraffin-embedded tissue sections. Ganglioside GM1 was detected in 5 of 19 SCLC tissues. These results suggest that ganglioside GM1 is expressed in SCLC cells.
