Anti-PLA2R autoantibodies in serum and IgG subclass deposits on glomeruli in undetermined atypical membranous nephropathy / 中华肾脏病杂志

ABSTRACT

Objective To investigate the characteristic of autoantibodies of M-type phospholipase A2 receptor (PLA2R) in serum and the glomerular IgG subclass deposits in undetermined atypical membranous nephropathy (MN) patients.Methods From Feb 2004 to Nov 2011,53 cases diagnosed as MN by kidney puneture biopsy in our hospital were included into the study.There were 20 undetermined atypical membranous nephropathy (UAMN),20 idiopathic membranous nephropathy (IMN) and 13 secondary membranous nephropathy (SMN) which were composed of lupus membranous nephropathy (LMN) and HBV related membranous nephropathy (HBV-MN).Clinlical and pathological characteristics were analyzed.The autoantibodies of PLA2R in serum were detected and the glomerular IgG subclass deposits were observed.Results (1) The average age underwent renal biopsy was (37.9±3.8) years of UAMN,(50.1±3.0) years of IMN and (49.5±4.5) years of SMN.The difference in onset average age at disease was significant between UAMN and IMN (P =0.0178).The female/male ratio (F/M) in UAMN,IMN and SMN was 0.8∶ 1,0.7∶1 and 0.6∶ 1(P ＞ 0.05).(2) Compared with SMN,the level of 24-hours urinary protein excretion (3.47 g vs 7.89 g,P =0.023),the ratio of amount urinary protein patients (50.0％ vs 84.6％,P=0.043),the level of serum IgG [(8.40±3.58) g/L vs (10.09±4.69) g/L,P =0.025] and the positive rate of ANA in serum (10.0％ vs 53.8％,P =0.006) in UAMN were all much lower.There were no significant statistical differences in serum albumin,serum creatinine,eGFR,positive rate of HBsAg,HBeAg or HCV,as well as the ratio of hypo-albuminemia and nephrotic syndrome among the three groups.(3) IF positive rate of IgA,IgM and C1q in UAMN were all significantly higher than that in IMN (P ＜ 0.01).There were no significant differences in IF positive rate of IgA,IgM,C1q,IgG and C3 between UAMN and SMN.The IF strength of IgA,IgG,IgM,C3 and C1q in UAMN showed no significant differences between UAMN and SMN.(4) The serum autoantibodies of PLA2R were only detected in 10 cases of IMN group (50％) with all the other cases negative.This detection rate of serum autoantibodies of PLA2R showed significant statistical differences among the three groups (P ＜ 0.01),but no differences between UAMN and SMN (the detection rate in both groups were 0％).(5) IgG1 deposits was the dominant IgG on the glomeruli in UAMN group (40％),as well as in SMN group (76.9％).IgG4 deposits was the dominant IgG on the glomeruli in IMN group (60％).The positive rate of IgG1 and IgG3 in UAMN showed no significant statistical differences when compared with IMN or SMN.The positive rate of IgG2 in UAMN was significantly lower than in SMN (30.0％ vs 69.2％,P ＜ 0.05).The positive rate of IgG4 in UAMN was significantly lower than in IMN (20％ vs 60％,P ＜ 0.05).The positive rate of IgG1,IgG2 and IgG3 in SMN were all significantly higher than in IMN.Conclusions None of the UAMN group had autoantibodies of PLA2R in serum,and IgG1 deposits was the dominant IgG subclass on the glomeruli which indicated the similarity with the SMN group.At the same time,UAMN was significantly different from SMN in clinical manifestations.