Cell-cell interaction and polarity of epithelial cells: specific perturbation using a monoclonal antibody.

With functional assays we selected a monoclonal antibody (anti-Arc-1) that perturbs specific cell-cell contacts of MDCK epithelial cells in tissue culture. The cells loosen their tight junctions, become uncoupled, and their polarity is abolished. Several findings show that the corresponding antigen appears to be a cell-surface protein of MDCK epithelial cells but not of other established cell lines: radioactively labeled antibody could be absorbed on the surface of intact cells; immunoscanning electron microscopy showed a homogeneous surface distribution of the antigen; and the antigen was extractable from the cells by EDTA. Absorption on Western blots and gel filtration showed antigenicity at 130 and 40 kd. This study shows that the hybridoma technique, in combination with functional screening of the monoclonal antibodies, allows the identification of new and specific molecules involved in cell-cell adhesion.