Visualization of cell-substratum adhesion plaques by antibody exclusion

We report on an antibody exclusion method for detecting cell adhesion plaques. Substrata coated by plasma fibronectin )pFN) appeared uniformly fluorescent when analyzed by indirect immunofluorescence using a specific anti-pFN antibody. When cells that had spread on the substrata were permeabilized and analyzed by indirect immunofluorescence, areas of non-fluorescence were apparent beneath the cells and in focal streaks along the cell margins. The nonfluorescent focal streaks were coincident with adhesion plaques visualized by interference reflection microscopy.