Phagocytotic activities of latex beads by FRTL cell: possible interaction of cell surface glycoprotein

We investigated the phagocytic activity of cultured rat thyroid cells (FRTL) by using latex beads. FRTL cells ingested many carboxylate-modified polystyrene latex beads (c-latex beads), which had carboxyl residues on the surface, whereas they ingested few polystyrene latex beads (p-latex beads), which had no electrostatic charge. Phagocytotic activity of c-latex beads was stimulated by TSH in a dose-related manner. Dibutyryl, 8-bromo-cAMP, and forskolin also stimulated this process. Tunicamycin significantly inhibited dibutyryl cAMP-stimulated phagocytotic activity of c-latex beads by FRTL cells. N-acetylglucosaminidase also inhibited dibutyryl cAMP-stimulated phagocytosis. These results suggest that the interaction between negative surface charge of c-latex beads and positive surface charge probably induced by N-acetylglucosamine in the cell surface glycoprotein, might play an important role in the phagocytosis of FRTL cells.