Circulating antibodies against M-type phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A in Chinese patients with membranous nephropathy.

BACKGROUND: M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) have recently been identified as target antigens for patients with idiopathic membranous nephropathy (IMN). The prevalence of PLA2R and THSD7A in the serum of MN patients deserves further investigation.

METHODS: Here, we studied the presence of anti-PLA2R and anti-THSD7A antibodies in patients with biopsy-proven IMN (n = 212), secondary membranous nephropathy (SMN, n = 118), and other kidney diseases (n = 84). The progress of 49 IMN patients [anti-PLA2R(+), n = 27; anti-THSD7A(+), n = 6; anti-PLA2R(-) and anti-THSD7A(-) dual negative, n = 16] who received immunosuppressive therapy was observed for 12 months. Serum concentrations of antibodies against PLA2R and THSD7A were detected using an indirect immunofluorescent assay.

RESULTS: One hundred fifty-two (71.7%) IMN patients and 11 (9.3%) SMN patients were identified as anti-PLA2R(+) anti-THSD7A(-). Five (2.4%) IMN patients and two (1.7%) SMN patients were identified as anti-THSD7A(+) anti-PLA2R(-). One of the IMN patients was identified as anti-PLA2R(+) and anti-THSD7A(+). The rate of partial remission was lower in anti-PLA2R(+) patients than in anti-PLA2R(-) patients 3 months (P = 0.045) and 6 months (P = 0.006) after immunosuppressive therapy. The rate of complete remission was lower in anti-PLA2R(+) patients than in anti-PLA2R(-) patients 12 months (P = 0.037) after immunosuppressive therapy.

CONCLUSIONS: The serum concentration of anti-PLA2R antibodies may be used as a sensitive and specific marker for diagnosing IMN. Immunosuppressive therapy is more effective for IMN patients who are anti-PLA2R(-) than for those who are anti-PLA2R(+).