Inhibition of endogenous peroxidase for the immunocytochemical demonstration of intermediate filament proteins (IFP).

The necessity for minimally fixed and processed cell and tissue preparations for immunocytochemical studies of sensitive antigens such as lymphocyte surface markers is well recognised. In order to avoid methanol and hydrogen peroxide, which have been shown to be deleterious for certain antigens, various compounds have been proposed for blocking endogenous peroxidase activity (EPA) in tissue preparations which are to be used in immunoperoxidase reactions. In the present study the deleterious effect of methanol/H2O2 on intermediate filament proteins was demonstrated in both frozen sections and paraffin-embedded tissue. The use of alternative reagents for the non-deleterious blocking of EPA is recommended for immunocytochemical staining with antibodies against intermediate filaments.