Electron microscopic evidence of surface immunoglobulins in Yoshida ascites sarcomas and ascites hepatomas

Yoshida ascties sarcoma and its variants and several azo dye-induced ascites hepatomas of rats were examined by an immuno-peroxidase technique to demonstrate surface immunoglobulins. More than 60% of the tumor cells in 8 ascites tumors showed positive surface staining (Group A), whereas the other 9 tumors were less than 15% positive (Group B). One tumor showed 34% positive reaction. The staining did not show capping. Six of the 8 Group-A tumors were single cell type, while 5 of the 9 Group-B tumors were island type. Intravenous transplantation rate was very low (less than 10%) in 2 of the 6 Group-B tumors, but only 1 of the 7 Group-A tumors showed moderately low (40%) intravenous transplantation rate. All of the 8 Group-A tumors showed survival period of less than 35 days after intraperitoneal transplantation, while the survival period was more than 45 days in 3 out of the 9 Group-B tumors.