Laboratory extensively applied enzyme-linked immunosorbent assay (ELISA) to measure anti-phospholipase A2 receptor antibodies (PLA2R-abs) since its diagnostic significance on PLA2R related primary membranous nephropathy (PLA2R-related pMN) was discovered. However, PLA2R-abs determined by ELISA (PLA2R-ELISA) could infrequently yield inconclusive results, specifically a grey-zone defined as PLA2R-abs ranging from 2 to 20 RU/mL. Recently, researchers suggested that double-check grey-zone PLA2R-abs by indirect immunofluorescence (IIF) could improve diagnostic accuracy. We evaluated the diagnostic performance of PLA2R-IIF in assessing PLA2R-related pMN and summarized clinicopathological characteristics of grey-zone population to provide more evidence for clinical practice.

Clinicopathological characteristics of patients with low titer anti-phospholipase A2 receptor antibodies verified by indirect immunofluorescence assay