Abstract
Introduction: Autoantibodies against phospholipase-A2 Receptor (PLA2
R), a normally
occurring antigen presented on podocyte membranes, have recently been implicated in the
pathology of membranous nephropathy (MN).
Objectives: In this observational study, we have evaluated the correlation of patient’s disease
activity against serum levels of anti-PLA2
R in patients with primary and secondary MN in a
North Indian cohort.
Patients and
Methods: We measured serum anti-PLA2
R antibody by ELISA in 63 adult
patients with MN. Out of these 63 patients, the majority (58) had primary MN (pMN) and the
remaining five had secondary MN (sMN).
Results: Around 55.2% had detectable anti-PLA2
R autoantibodies (63% in those with newonset
pMN, 67% in patients with relapse and 3% in patients in remission). However, all
patients with refractory pMN (n=4) were anti-PLA2
R negative. There was significantly higher
anti-PLA2
R positivity in active stage of disease in contrast to those in remission (P<0.001).
Autoantibody level was proportional to the disease activity, with a trend towards significance
(P=0.052). Hypoalbuminemia and proteinuria were also significantly worse in the antiPLA2
R positive patients. All patients with sMN tested negative for anti-PLA2
R autoantibodies.
Conclusion: PLA2
R is a major target antigen in Indian population with idiopathic MN. AntiPLA2
R positivity is a specific tool to detect idiopathic MN, and its levels correspond well with
other disease activity markers. In addition, anti-PLA2
R antibody was negative in refractory
pMN, which suggests the existence of additional autoantibodies in this subgroup, with a
different target antigen. These autoantibodies may be resistant to the currently recommended
immunosuppressants for the disease, thus the refractory nature of the disease.