CELL-FREE ASCITIC FLUID PREVENTS LOSS OF CELL-SURFACE SIALIC-ACID FROM ZAJDELA ASCITIC HEPATOMA-CELLS IN CULTURE

In the Zajdela Ascitic Hepatoma (ZAH), a rat tumor, high levels of cel l surface sialic acid residues are present which masked the immunogeni city of the cells. We have shown here that cell surface sialic acid le vel goes down rapidly when ZAH cells are put in culture. The reduction in surface sialic acid levels is due to a decrease in sialic acid res idues on the major sialylated glycoprotein, gp 120, as well as a decre ase in gp 120 polypeptide. The loss of sialic acid from the cultured c ells is reduced if the cells are cultured in the presence of cell free ascitic fluid from ZAH tumor.