Diagnostic accuracy of immunofluorescence versus immunoperoxidase staining to distinguish immune complex-mediated glomerulonephritis and C3 dominant glomerulopathy

Abstract

Aims

Membranoproliferative glomerulonephritis (MPGN) has been reclassified from an electron microscopy to an immunofluorescence (IF) based semi quantitative classification with immunoperoxidase (IP) technique as a backup option when IF is not possible. However, no data are available on the interobserver variability, the correlation and the reclassification of MPGN based on these two techniques.

Methods & Results

We retrospectively analyzed cases of type 1 MPGN. We repeated IF and performed IP for IgG, kappa, lambda, C3c, and C4d in 35 renal biopsies among which 19 biopsies having a matched IP and IF. We observed a substantial to near perfect agreement among the 7 observers for both IF and IP (W coefficients from 0.66 for IF lambda to 0.89 for IF C4d). Of the 19 cases with matching IP and IF, 5 (26%) turned out to have a different diagnosis on IF as compared to IP. Also, C4d ability to discriminate immune complex-mediated GN (ICGN) from C3 glomerulopathy (C3G) was poor with an area under the curve of 0.44 (95% CI = 0.24 - 0.63) and 0.66 (95% CI = 0.50 - 0.81) for the receiver operating characteristic curves of IF and IP respectively. Limitations include that no clinical data regarding complement activation were available.

Conclusion

The diagnosis of ICGN versus C3GN depends on the immunochemical technique used. Also, the use of C4d failed to discriminate ICGN from C3G in our study. Further validation studies are required to avoid misdiagnosis based on kidney biopsy.

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from #ORL-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2wKTcfJ