Reply

Sir, As Dr Mubarak correctly observes, the study of immunohistological findings in the Oxford Classification of IgA nephropathy cohort [1] is based on review of the original pathology reports and not of the slides. This was necessary, as there was no access to the original diagnostic material which, in almost all cases, was immunofluorescence (IMF) on frozen sections. As a result, the quality of immunohistological data was potentially limited by interobserver variation between the reporting pathologists. In view of this methodological flaw, it is particularly impressive that strong correlations were found between the IMF findings and light microscopical changes. We agree that if immunohistology is to be included in a classification of IgA nephropathy, then the issue of IMF definitions and reproducibility first needs to be addressed. Whilst there are several studies that have assessed interobserver agreement in the interpretation of the histological changes in renal diseases [2–4], there are few such studies applied to renal immunohistology. Interobserver concordance in the interpretation of C4d and SV40 T-antigen positivity in renal transplant biopsies has recently been reported [5, 6]. Similar studies applied to glomerular IMF and immunohistochemistry in native renal disease are lacking. Some researchers suggest that image analysis is superior to subjective interpretation of renal IMF. Interestingly, a recent study reported that, in IgA nephropathy, the presence of adverse histological prognostic features correlated with intensity and total optical density of fluorescence measured using image analysis software, but not with semiquantitative scoring [7]. Electron microscopy (EM) was not included in the Oxford Classification because neither the reports nor the images were available for most biopsies. We agree that further investigation of the ultrastructural changes in IgA nephropathy is required, in particular correlation with light microscopy and clinical outcome. The future inclusion of ultrastructural features in the Oxford Classification will depend on evidence that EM provides added clinical value. Such evidence is lacking at present, reflected in the limited use of EM in many centres. Conflict of interest statement. None declared.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.