C4d immunohistochemical staining is a sensitive method to confirm immunoreactant deposition in formalin-fixed paraffin-embedded tissue in membranous glomerulonephritis
J. Fernando Val-Bernal1, M. Francisca Garijo1, Daniel Val1, Emilio Rodrigo2 and Manuel Arias2
1Department of Anatomical Pathology and 2Nephrology Service, Marqués de Valdecilla University Hospital, Medical Faculty, University of Cantabria, Santander, Spain.
Offprint requests to: Fernando Val-Bernal, MD, PhD, Departamento de Anatomía Patológica, Hospital Universitario Marqués de Valdecilla, Avda. Valdecilla s/n, 39008 Santander, Spain. e-mail: firstname.lastname@example.org
Summary. Although the diagnosis of membranous glomerulonephritis (MGN) may be suspected on routine histology of formalin-fixed paraffin-embedded tissue, fresh-frozen tissue must be used to show the immunologic nature of the process by direct immunofluorescence (IF). The efficiency of IF or immunoperoxidase (IP) detection of IgG and C3 using paraffin sections is controversial. This study was designed to evaluate whether glomerular C4d deposition using an IP method in formalin-fixed paraffin-embedded tissue may be a useful marker for MGN. We showed characteristic glomerular, granular basement membrane deposition of C4d in 31 (100%) cases of idiopathic MGN and in 5 cases (100%) of pure class V membranous lupus nephritis, in which we had a positive diagnosis of the lesions for conventional IF study. Control cases were negative. Nineteen cases of different glomerulopathies, including IgA nephropathy, primary type I membranoproliferative glomerulonephritis, focal segmental glomerulosclerosis and minimal change disease showed diverse reproducible patterns of C4d deposition, without intrinsic background. Our results indicate that staining of formalin-fixed paraffin-embedded tissue for C4d can be used for confirmation of granular basement membrane immunoreactant deposition in cases of MGN. This proved to be a reliable method that could potentially obviate the need for rebiopsy in cases with absence of glomeruli in renal frozen sections or when other adjunct IF or IP methods on paraffin sections are negative. C4d immunostaining, using an IP method, deserves a place as an adjunct method in the biopsy diagnosis of MGN. Histol Histopathol 26, 1391-1397 (2011)
Key words: C4d, Glomerulonephritis, Immuno-peroxidase methodology, Immunofluorescence method, Membranous glomerulonephritis, Paraffin embedded section, Polyclonal antibody