Application of the immunoperoxidase technique to formalin fixed, paraffin embedded kidney biopsies.

Different immunohistological methods were compared in 30 renal biopsy cases. The direct immunoperoxidase method gave identical results with immunofluorescence in 88% concerning IgG and C3, while IgA, IgM and fibrinogen have been identically detected by the PAP method in 82%. The non-identical results of the direct method consisted, with one exception, of negative readings, while the non-identical PAP readings were positive with two exceptions. Thus the trypsin-immunoperoxidase method proved to be well applicable on paraffin embedded formalin fixed material. In 10 cases the HRP-labelled direct method was applied also to fresh, frozen sections. It gave almost entirely identical results to immunofluorescence.