Retardation of fading and enhancement of intensity of immunofluorescence by p-phenylenediamine.

The effects of p-phenylenediamine (PD) on the extinction and intensity of fluorescence and on antigen binding in immunofluorescence microscopy was investigated. Visual and photometric comparison of tissue sections reacted sequentially with polyclonal or monoclonal antisera and appropriate fluorochromes and mounted with and without PD indicated that PD both prolonged and intensified fluorescence without evident effect on antibody binding.