Table 4.
Studies using the technique of immunofluorescence on enzyme digested paraffin embedded tissue in literature
| Ref. | Year | Enzyme used | Cases (n) | IF panel applied | Significant results |
| [2] | 1976 | Trypsin for 120 min | NA | Immunoglobulins and complement | Feasible to demonstrate immunoglobulins but not complement Reduced background immunofluorescence |
| [5] | 1979 | Trypsin | 52 renal biopsies | IgG, IgA, IgM, C3, Fibrinogen | Accurate detection of immunoglobulins (90%) and complement (75%) in comparison with IF on frozen |
| [6] | 1980 | Trypsin | 21 (LN, MN, IgAN) | IgG, IgM, IgA | IF on trypsin-digested tissue was as sensitive as IF-F for immunoglobulins but less sensitive for complement |
| [7] | 1980 | Pepsin (0.4%) and trypsin | Experimental mice model of anti GBM disease | IgG | Pepsin +/- trypsin digestion better than trypsin alone Enzyme digested tissue showed trivial decrease in sensitivity but good preservation in comparison with IF on frozen |
| [8] | 1989 | Pronase (0.75 g/L for 60 min at 37 °C) | IgAN (10), MN (8), Proliferative LN (10) | IgG, IgA, IgM, C3, C1q | Correct diagnosis possible in all cases Better structural details and less fading of IF Lower intensity staining for C3 Retrospectively performed digestion on 1 and 2 yr old blocks, satisfactory in 86% cases |
| [9] | 2005 | Microwave treatment (10 min) followed by Protease VII (0.05% for 30/60 min) Trypsin (0.25% for 120 min) | IgAN (7), LN (7), MN (7), MPGN (3) | IgG, IgA, IgM, C3 | Microwave treatment followed by protease digestion better than trypsin digestion Diagnostic immunoglobulin found in more than 80% cases |
| [10] | 2006 | Pronase (0.75 g/L for 60 min at 37 °C) | MN (8), MPGN (5), LN (5), PIGN (5), IgAN (8), Cryo GN (5), Fibrillary GN (5), Anti GBM (5), Cast nephropathy (5), Amyloid (5), LCDD (5), LCFS (10) | IgG, IgA, IgM, C3, C1q, kappa and lambda | Diagnostic utility in 83% cases Useful in dysproteinemia related renal disease particularly LCFS Less sensitive for staining with C3 in MPGN type I, Cryo GN, PIGN Less sensitive for IgG in MGN and anti-GBM disease |
| [11] | 2007 | Proteinase XXIV | LN (5), antiGBM (5), MN (9) | NA | IF-P on proteinase XXIV is more sensitive than IF-P with pronase In LN, better intensity staining for C1q and IgG In anti GBM, 80% sensitivity for detection of IgG In MGN, 55% sensitivity for detection of IgG |
| [12] | 2009 | Microwave treatment and/or Proteinase K – (30 or 60 min) | IgAN (24), MN (22), LN (24) | IgG, IgA, IgM, C3 | Rate of agreement between immunofluorescence on paraffin sections and immunofluorescence on frozen sections with respect to the presence of IgA was 56.5%, IgM - 44.4%, IgG - 73.9%, and C3 - 51.5% IF-P may be used as a salvage technique when frozen tissue is not available |
| [13] | 2011* | Trypsin (30 min), Pepsin | IgAN (20), MN (25) | IgA, IgG, HBsAg, HbcAg | Trypsin digestion better than pepsin digestion IF-P slightly weaker signal than IF-F |
| [14] | 2012 | Heat - Tris/Citrate buffer Pronase RTU ( 60 min at 37 °C) | LN (15), MN (11), IgMN (10), MPGN (2), IgAN (2) | IgG, IgA, IgM, C3, C1q | Heat based retrieval using Tris buffer showed superior results Pronase digestion shows less sensitivity for detection of immunoglobulins and complement |
| [15] | 2015 | Proteinase K for 20 min | 304 cases (207 cases as salvage and 97 cases for antigen unmasking ) | IgG, IgA, IgM, C3, C4, C1q, fibrinogen, kappa and lambda | Not only a good salvage technique but prevents misdiagnosis due to masked immune complex or light chain deposition |
LN: Lupus nephritis; MN: Membranous nephropathy; IgAN: IgA nephropathy; IgMN: IgM nephropathy; MPGN: Membranoproliferative glomerulonephritis; anti GBM: Anti glomerular basement membrane nephritis; PIGN: Post infectious glomerulonephritis; Cryo GN: Cryoglobulinemic glomerulonephritis; LCDD: Light chain deposition disease; LCFS: Light chain fanconi syndrome; RTU: Ready to use; HBsAg: Hepatitis B surface antigen; HbcAg: Hepatitis B core antigen; IF: Immunofluorescence.