Protein-A gold particles as markers in replica immunocytochemistry: high resolution electron microscope...

Due to their high atomic number contrast in transmission electron microscopy, gold particles are ideal markers in surface replicas of cultured cells. The suitability of protein-A-coated gold particles in replica immunocytochemistry for labelling surface antigens is demonstrated using measles virus-infected cells as a model system. Labelled areas can easily be distinguished from unlabelled areas, and even markers positioned in the evaporation shadow of large structures can be accurately identified, which is a prerequisite for an exact quantification and mapping of antigen. In addition, the ultrastructure of labelled areas can still be visualized because of the small size of the marker.