Immunofluorescence staining in unfixed or fixed renal biopsy specimens from patients with diabetic nephropathy

Immunofluorescence staining in unfixed or fixed renal biopsy specimens were evaluated in nine patients with diabetic nephropathy in order to elucidate if immunofluorescence staining is applicable in fixed renal tissues in such patients. Renal biopsy specimens were embedded in gelatin or paraffin matrix. Renal biopsy specimens embedded in paraffin matrix were digested with 0.05% protease. Immunofluorescent studies of kidney tissues were performed by staining with FITC-labeled heavy chain specific anti-human IgG, IgA, IgM, acute phase reactant (APR) proteins such as alpha 1-anti-trypsin (alpha 1-AT), haptoglobin (Hpt) and beta-lipoprotein (beta-Lp) antisera, and then examined with a fluorescent microscope. Linear and nodular deposition of IgG, IgA, IgM, alpha 1-AT, Hpt, and beta-Lp were observed in the glomerular capillary walls of the renal specimens embedded in paraffin matrix. The staining patterns in specimens embedded in paraffin matrix was similar to that embedded in gelatin matrix. There was no significant difference in the intensity or distribution of IgG, IgM, alpha 1-AT, and beta-Lp deposition among the two different conditions of immunofluorescence in patients with diabetic nephropathy. It was suggested that immunofluorescence staining in renal biopsy specimens embedded in paraffin matrix after digestion with protease is useful for the evaluation of IgG, IgM, APR proteins, and beta-Lp in glomeruli from patients with diabetic nephropathy.