False-positive anti-PLA2R ELISA testing in patients with diabetes mellitus

We found the study by Hoxha et al., “False Positivity for PLA2R1 Antibody Measured by ELISA in a Nephrotic Patient With No Membranous Nephropathy,” to be of interest. 1 Hoxha E. Reinhard L. Castedello T. Becker J.U. False positivity for PLA2R1 antibody measured by ELISA in a nephrotic patient with no membranous nephropathy. Kidney Int. 2023; 103: 411-415 Google Scholar We identified 2 similar patients with biopsy-proven diabetic nephropathy with false-positive phospholipase A2 receptor (PLA2R) testing by enzyme-linked immunosorbent assay (ELISA; patients 1 and 2 in Table 1). Within a 5-year period, we had 6 of 5058 serology cases that were PLA2R-positive by ELISA and negative by indirect immunofluorescence assay (0.12%). On subsequent kidney biopsy, 2 had membranous nephropathy and 2 showed nodular diabetic glomerulosclerosis. The remaining 2 patients did not undergo biopsy, including 1 patient with a history of diabetes mellitus and 1 lost to follow-up (Table 1). Table 1Patient characteristics with positive PLA2R ELISA and negative IFA antibody testing Patient no. Age, yr Sex PLA2R titer, IU/ml Kidney biopsy diagnosis Time from serology to biopsy 1 66 M 85.7 Nodular diabetic glomerulosclerosis 1 mo 2 a Patients 2 and 3 had 2 blood samples tested at different times with the same pattern of results. 76 M 158.1; 182.9 Nodular diabetic glomerulosclerosis 4 mo 3 a Patients 2 and 3 had 2 blood samples tested at different times with the same pattern of results. ,b Patient 3 was sent in consultation with the manufacturer with the same results. 57 M 471; >1500 PLA2R-positive membranous nephropathy 2 yr 4 c Patient 4 was tested at a later date (2 months) with positive testing by both IFA and ELISA. 78 M 116.1 PLA2R-positive membranous nephropathy 2 mo 5 d Patient 5 did not undergo kidney biopsy but had a history of poorly controlled diabetes mellitus. 71 M 214.6 N/A, did not undergo kidney biopsy N/A 6 72 F 127.3 N/A, did not undergo kidney biopsy N/A ELISA, enzyme-linked immunosorbent assay; F, female; IFA, indirect immunofluorescence assay; M, male; N/A, not available; PLA2R, phospholipase A2 receptor. a Patients 2 and 3 had 2 blood samples tested at different times with the same pattern of results. b Patient 3 was sent in consultation with the manufacturer with the same results. c Patient 4 was tested at a later date (2 months) with positive testing by both IFA and ELISA. d Patient 5 did not undergo kidney biopsy but had a history of poorly controlled diabetes mellitus. Open table in a new tab ELISA, enzyme-linked immunosorbent assay; F, female; IFA, indirect immunofluorescence assay; M, male; N/A, not available; PLA2R, phospholipase A2 receptor. False positivity for PLA2R1 antibody measured by ELISA in a nephrotic patient with no membranous nephropathyKidney InternationalVol. 103Issue 2PreviewThe discovery of autoantibodies against M-type phospholipase A2 receptor (PLA2R1)1 as the main cause of membranous nephropathy (MN) has revolutionized diagnosis, prognostication, and treatment approaches in patients with MN.2 Different assays have been established for the detection of circulating PLA2R1 antibodies.2 Although Western blot is more sensitive, enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence test (IIFT) are commercially widely available and routinely used for the diagnosis and to make treatment decisions in patients with MN. Full-Text PDF