These findings highlight the need for the IgG subclass change to IgG4 for the anti-PLA2R antibodies to become pathogenic. 1:274, P < 0.001). IgG2(45.1%) was predominant in organic antibodies, while IgG4 was predominant in Ab + group (45.7 vs. 25.0%,P< 0.001). IgG1 was raising from organic antibodies to Ab- and Ab + organizations. The affinity of organic antibodies was lower than that of individuals (KD: 641.0 vs. 269.0 vs. 99.6 nM,P= 0.002). The antibody titer, affinity, and IgG4 percentage were associated with the severity of proteinuria and the phases of membranous lesion. == Conclusions == The natural anti-PLA2R antibodies exist in healthy plasma. The antibody titer, IgG subclass, and affinity may participate in the pathogenesis of anti-PLA2R antibodies. Keywords:Membranous nephropathy, Phospholipase A2 receptor, Natural antibodies, Antibody titer, IgG subclass, Antibody affinity == Intro == Main membranous nephropathy (MN) is definitely a kidney-specific autoimmune disease characterized by the antibodies towards podocyte antigens and the formation of in situ immune complex within the subepithelial area [1]. The major target antigen VER 155008 is definitely M-type phospholipase A2 receptor (PLA2R), with anti-PLA2R antibodies detectable in approximately 7080% of the individuals with main MN [2]. The pathogenesis of VER 155008 anti-PLA2R antibodies on MN has been shown using the transgenic mice expressing murine full-length PLA2R on podocytes, which can be induced medical manifestations and pathological cells manifestations of MN by passive immunization of anti-PLA2R antibodies [3]. In medical practice, anti-PLA2R antibodies CDX4 have been demonstrated to be close associations with the severity of proteinuria and the prognosis of kidney function. The higher antibody level is definitely associated with a lower chance of remission accomplished spontaneously or after immunosuppressive therapies, and a higher risk of worsening kidney function [46]. The switch of anti-PLA2R antibodies is definitely parallel or precede the switch of medical manifestations and may predict the disease progression [79]. The distributing of epitopes is also associated with a poor prognosis of the disease [10]. However, its event is definitely controversial and the prognosis might be more related to antibody level [11]. The mechanism of anti-PLA2R antibodies production remains unclear. Auto-reactive B cells [12,13] and natural autoantibodies [14] interacting with self-antigens, such as glomerular basement membrane [15], neutrophil cytoplasmic antigens [16], thyroglobulin [17], insulin [18], and DNA [19], have been reported in healthy individuals. The living of immunoreactive soluble PLA2R in healthy plasma [20] and the ability of podocytes to secrete vesicles comprising PLA2R [21] provide routes for the engagement of PLA2R with the immune system. Circulating PLA2R antibodies have been detectable weeks to years before the recorded proteinuria and biopsy-proven analysis VER 155008 in MN individuals [22]. Consequently, we hypothesized the natural antibodies against PLA2R may exist in healthy individuals and the variations between natural antibodies and pathogenic antibodies in MN individuals may offer hints for an in-depth understanding of the immune disorders of PLA2R connected MN. In the current study, we purified anti-PLA2R antibodies by affinity chromatography from your plasma of healthy individuals and MN individuals, and compared the variations on their immunological features (antibody amount, titer, IgG subclass, and affinity), with the aim to explore the pathogenesis of anti-PLA2R antibodies. == Materials and methods == == Study population == A total of 30 individuals with PLA2R connected MN and eight healthy individuals were enrolled in this study. Kidney biopsy exposed granular deposit of IgG and C3 along glomerular capillary walls VER 155008 on immunofluorescence and the enhanced staining of PLA2R on immunohistochemistry, the glomerular basement membrane thickening on light microscopy, and the electron dense deposit within the subepithelial area on electron microscopy. The causes of secondary MN were excluded, including systemic lupus erythematosus, hepatitis B disease infection, malignancy, medication, heavy metal poisoning, etc. All the plasma were acquired on analysis before the treatments of steroids or immunosuppression, and maintained at 80 C. The circulating anti-PLA2R antibodies were detected by a commercial enzyme-linked immunosorbent assay (ELISA) kit (EUROIMMUN AG, Germany). 18 individuals were positive of anti-PLA2R antibodies (Ab + group, > 20 RU/ml) and 12 individuals were bad (Ab- group, < 14 RU/ml). All the healthy individuals.