(HealthDay News) – Two techniques can be used to measure antiphospholipase A2 receptor (aPLA2R) antibody titers in patients with idiopathic membranous nephropathy (iMN), with antibody titers indicative of outcome, according to research published online Sept 6 in the Journal of the American Society of Nephrology.
Julia M Hofstra, MD, of the Radboud University Nijmegen Medical Centre in the Netherlands, and colleagues compared indirect immunofluorescence testing (IIFT) and enzyme-linked immunosorbent assay (ELISA) for measuring aPLA2R antibody titers in 117 Caucasian patients with iMN and nephrotic-range proteinuria. The agreement between the tests was assessed, and the correlation between antibody titers and outcome was examined.
The researchers observed excellent concordance between the two tests, with 94% agreement. Using the IIFT method, 74% of patients tested positive for aPLA2R antibodies, compared with 72% who tested positive using ELISA. Antibody titer correlated with baseline proteinuria among aPLA2R-positive patients. Patients with the antibody titers in the highest tertile were much less likely to experience a spontaneous remission compared with those with the titers in the lowest tertile (4% vs. 38%). For the majority of patients, immunoglobulin G4 (IgG4) was the predominant subclass and IgG4 correlated with spontaneous remission (P=0.03).
“In summary, these data show high agreement between IIFT and ELISA assessments of aPLA2R antibody titer and highlight the pathogenetic role of these antibodies, especially the IgG4 subclass, given the observed relationships between aPLA2R titer, baseline proteinuria, and outcome,” the authors write.