Immunohistochemical detection of antibody in tissue sections of non-perfused and ex vivo-perfused organs using a tetrazolium alkaline phosphatase substrate.

We have used nitroblue tetrazolium (NBT) as a color reagent to localize antibody-bound alkaline phosphatase in frozen tissue sections. In the method described, NBT is reduced to a stable black diformazan reaction product that contrasts well with nuclear counterstains such as hematoxylin and stands out strongly in black and white photographs. We have found NBT to be a suitable color reagent for the alkaline phosphatase: anti-alkaline immunohistochemical technique. The reaction product also contrasts well with fast red and can therefore be used as second reagent for two color immunoenzyme studies. In this report, we describe a novel two color immunoenzyme method to assess the ex vivo binding of antibodies against Class II histocompatibility antigens in whole organs connected to a perfusion circuit.