Paraffin Immunofluorescence: A Valuable Ancillary Technique in Renal Pathology

Abstract

Immunofluorescence on frozen tissue is the gold standard immunohistochemical technique for evaluation of immune deposits in the kidney. When frozen tissue is not available or lacks glomeruli, immunofluorescence can be performed on paraffin tissue after antigen retrieval (paraffin immunofluorescence). Excellent results can be obtained by paraffin immunofluorescence in most immune complex–mediated glomerulonephritides and dysproteinemia-associated kidney lesions, and thus this technique has become a valuable salvage technique in renal pathology. Furthermore, new data have emerged suggesting that paraffin immunofluorescence can be used as an unmasking technique, as it is more sensitive than frozen tissue immunofluorescence in some kidney lesions, such as crystalline light chain proximal tubulopathy and is needed to establish the diagnosis of certain unique lesions, such as membranous-like glomerulopathy with masked IgG kappa deposits and membranoproliferative glomerulonephritis with masked monotypic Ig deposits. However, it is important to recognize and be aware of the limitations and pitfalls associated with paraffin immunofluorescence. These include poor sensitivity for detection of C3 deposits and for the diagnosis of primary membranous nephropathy. Here, we summarize the available techniques of paraffin immunofluorescence, review its role and performance as a salvage and unmasking technique in renal pathology, address its limitations and pitfalls, and highlight unusual forms of glomerulopathy that require paraffin immunofluorescence for diagnosis.

The Pathology of Amyloidosis in Classification: A Review

“…While immunofluorescence in frozen sections and immunohistochemistry in paraffin sections have traditionally been used for amyloid typing, mass spectrometry has emerged as the method of choice for the typing of amyloid proteins, in particular in paraffin sections [6][7][8][9][10][11][12][62][63][64][65][66][67][68][69][70][71][72].…”

“…2e, f). More recently, the application of paraffin-section immunofluorescence has been reported as superior to routine paraffin-section immunohistochemistry, in particular for the detection of AL [68][69][70]. Moreover, some centers continue to use immunogold labelling with good results and the application of antibodies raised against free light chains (as opposed to conventional antibodies) may also yield better results [73,74].…”

Context-dependent roles of complement in cancer

“…Well characterized and validated antibodies with known fragment specificity should be used. Detection of complement and its activation fragments is performed in routine pathology laboratories and the difficulties to work with paraffin embedded tissues are well documented 108 . Nevertheless, nowadays reliable protocols exist for staining of complement components and activation fragments in paraffin-embedded tumor tissue 21 , with antibodies, validated by competition tests with intact proteins or fragments.…”

Lost in Transportation: Calcium Oxalate Crystals in Kidney Biopsy Specimens Fixed in Michel Medium May Disappear

“…10,11 Interestingly, MTM tissue preservation has also been hypothesized to adversely affect the detection of monoclonal immunoglobulins; routine IF after MTM preservation fails to detect the deposits, while IF performed after protease digestion on paraffin sections yields positive results. 12 Our study is the first to show that MTM may also affect detection of chemical substances, such as CaOx crystals.…”