Antibody Labeling and the Choice of the Label

Abstract

In order for the antigen–antibody immunoreaction to be seen in the microscope, the antibody must take a label – enzyme, fluorophore, colloidal gold or biotin. An enzyme label can be visualized in the light microscope by means of enzyme histochemical methods via chromogenic reactions (see Sect. 2.3). A fluorophore label can be directly visualized in a fluorescent microscope (see Sect. 2.4). Electron-dense labels such as colloidal gold are visible in the electron microscope without further treatment (see Sect. 12.1). Biotin label can be exploited in light, fluorescence and electron microscopy in combination with ABC technique (see Sect. 6.2.1). Like biotin, some other haptens, such as digoxigenin (DIG) or dinitrophenol (DNP), can also be coupled to antibodies. For their visualization, enzyme- or fluorophore-conjugated secondary antibodies are affordable.