Immunofluorescence with dual microwave retrieval of paraffin-embedded sections in the assessment of human renal biopsy specimens.

Immunofluorescence of frozen tissue sections (IF-F) is a classic technique for renal immunopathologic examination. However, it has certain disadvantages, such as diffuse antigen distribution and few or even no glomeruli in the section. We developed a new technique of immunofluorescence staining using dual microwave retrieval in paraffin-embedded renal tissue sections (IF-DMP) and compared IF-DMP with IF-F in 406 renal biopsy samples. IF-DMP detected significantly more glomeruli than did IF-F (P< .001). There was no significant difference for the specificity and sensitivity in the detection of immunoglobulins, complements, κ, and λ between IF-F and IF-DMP. Concordant observations were 98% for all immunofluorescence, complements, κ, and λ staining and 100% for immunoglobulin staining. Both techniques were completely accurate in confirming diagnoses of various glomerular diseases. IF-DMP provided clearer images of tissue structure and more precise localization of antigens, and it is a suitable alternative for traditional IF-F in clinical renal immunopathologic diagnosis.