Cultured liver epithelial cells can incorporate monoclonal antibodies directed against intracellular cytokeratin structures without microinjection.

Abstract

T51B rat liver cells in the exponential phase of growth were arrested in late G1 by medium calcium deprivation, exposed to mouse monoclonal anti-cytokeratin (Mr = 55,000) by addition of the antibody to the medium, induced to enter the S phase by readdition of 1.5 mM calcium, and incubated for a further 18 h. After fixing and staining with FITC-conjugated anti-mouse IgG, the cells exhibited an intact intracellular cytokeratin-staining pattern. No effect of antibody was observed on entry of cells into the S phase. These results show that rat liver-derived epithelial cells can actively take up macromolecules like cytokeratin antibodies without microinjection.