Removal of endogenous peroxidase activity from cryostat sections for immunoperoxidase visualisation of monoclonal antibodies.

The interpretation of immunoperoxidase staining of frozen tissue sections can be severely limited by the presence of endogenous peroxidase enzymes in the tissue. Previously recommended methods of reducing this enzyme activity were examined, but were found to be unsatisfactory when applied to the small intestine. A method, which effectively eliminates this background staining but which does not interfere with the binding of monoclonal antibodies to various tissue components, is described. This method may prove useful in immunoperoxidase studies of other tissues in which high levels of endogenous peroxidase are present.