A Comparative Study of Immunofluorescence on Formalin-Fixed, Paraffin-Embedded Versus Fresh Frozen Kidney Biopsy

Abstract

Background Immunofluorescence techniques done on formalin-fixed, paraffin-embedded tissue can serve as salvage techniques in cases where immunofluorescence on the frozen section may not be adequate or available. The present study was undertaken to assess the diagnostic utility of paraffin immunofluorescence by proteinase K digestion on renal biopsy compared to fresh frozen immunofluorescence. Methodology The paraffin immunofluorescence by proteinase K digestion of paraffin-embedded renal biopsy (IF-FFPE) was standardized and compared with the immunofluorescence on fresh frozen tissue (IF-Frozen). A total of 50 cases of the native renal biopsy were included in the study, and their intensity for fluorescein isothiocyanate-labeled IgA, IgG, IgM, C3, kappa, and lambda was compared. Results A total of 50 cases of the native renal biopsy were included in the study, and their intensity for fluorescein isothiocyanate-labeled antibodies of IgA, IgG, IgM, C3, kappa, and lambda was compared. The difference of 2+ intensity of antibodies between IF-FFPE and IF-Frozen was noted mainly in lupus nephritis (15%), followed by IgA nephropathy (10%) and membranoproliferative glomerulonephritis (7%). IF-FFPE showed a sensitivity of 90.3%, 91.8%, 82.7%, 81.1%, 92.1%, and 94.6% for IgA, IgG, IgM, C3, kappa, and lambda, respectively, whereas specificity was 100% for IgA, IgG, C3, kappa, and lambda and 95.2% for IgM. Conclusions Immunofluorescence techniques done on formalin-fixed, paraffin-embedded tissue can serve as salvage techniques in kidney biopsies.

An Unusual Case of Immune Complex-Mediated Membranoproliferative Glomerulonephritis as Renal Manifestation of Idiopathic Hypereosinophilic Syndrome: A Case Report and Literature Review

“…To have a more complete study of the case, it would have been ideal to perform IF on formalin-fixed, paraffin-embedded tissue. Das N. et al [ 27 ] conclude that this technique can increase the sensitivity and specificity of detecting immunoglobulins and complement deposits in RB. Unfortunately, we do not have access to this technique in our hospital.…”

Diagnostic Utility of Immunofluorescence on Formalin-Fixed Paraffin-Embedded Skin Biopsy

“…[ 5 ] One of the masking mechanisms of formalin on immunofluorescence is protein cross-linking, which prohibits FITC-conjugated antibodies from interacting with the antigens during immunofluorescence on formalin-fixed, paraffin-embedded tissue. [ 6 7 ] Therefore, unmasking of the antigens is necessary for formalin-fixed, paraffin-embedded tissues using a variety of methods, such as enzyme digestion and heat treatment. [ 7 8 ] Proteinase K, trypsin, and heat-induced enzyme retrieval have been used for antigen retrieval in paraffin blocks of skin biopsies at various temperatures, concentrations, and times.…”