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Abstract: FR-PO863

Determination of Serum Anti-PLA2R and Anti-THSD7A Antibodies and Tissue Anti-PLA2R in Brazilian Patients with Primary and Lupus Membranous Nephropathy

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Author

  • Battaini, Ligia Costa, HCFMUSP, São Paulo, Brazil
Background

Membranous Nephropathy (MN) is a common cause of nephrotic syndrome in adults. In Brazil, it is the second most frequent cause of glomerulopathies in biopsies registries. Incidence variations among the various studies may reflect patterns of biopsy indication in different countries, but it may also be related to socioeconomic, ethnic or environmental characteristics. In the past years, the role of anti-phospholipase A2 (anti-PLA2R) receptor autoantibodies and the antibody against THSD7A (thrombospondin type 1 domain-containing protein 7A) in the pathogenesis of idiopathic MN were described. The determination of these serum antibodies and renal tissue anti-PLA2R antibodies have not yet been performed in the Brazilian population.

Methods

Blood samples were collected from 28 patients diagnosed with MN, 17 patients with Lupus Membranous Nephropathy (LMN) and 8 patients with Focal and Segmental Glomerulosclerosis (FSGS), confirmed by renal tissue biopsy (OM and IF). The serum anti - PLA2R antibody was measured by the ELISA and IIFT techniques and antibodies against THSD7A by IIFT. In addition, immunohistochemistry was performed in paraffin blocks to identify the anti - PLA2R antibody in these patients.

Results

All 17 patients with LMN and the 8 patients with FSGS were negative for anti - PLA2R and anti - THSD7. A total of 28 patients with MN tested negative for anti - THSD7A. Among the patients with MN at admission, there was a positivity of 54% by IIFT and 39% by ELISA, considering VR of 20 RU/ml. When we reduced the ELISA reference value to 14 RU/ ml the sensitivity of the test equals the IIFT test. The specificity of both methods was 100% in this sample. Immunohistochemistry was performed in 24 of the 28 patients with NM, 15 (63%) presented positive labeling for the antibody in renal tissue. Of the 15 patients with tissue positivity, 13 tested positive for the antibody in the serum.

Conclusion

In this Brazilian population of MN patients, there was 54% positivity for anti - PLA2R. The IIFT and ELISA technique has the same sensitivity when considering the RV of 14 RU/ml for the ELISA. The sensitivity of immunohistochemistry in the tissue was greater than the serum antibody anti – PLA2R dosage.

Funding

  • Government Support - Non-U.S.