Phospholipase A2 Receptor–Related Membranous Nephropathy and Mannan-Binding Lectin Deﬁciency

BRIEF COMMUNICATION www.jasn.org

†‡ | Stéphane Bally,* Hanna Debiec, Denise Ponard,§ Frédérique Dijoud, John Rendu,¶ †‡ Julien Fauré,¶ Pierre Ronco, ** and Chantal Dumestre-Perard§

*Service de Néphrologie Dialyse, Centre Hospitalier Métropole Savoie, Chambery, France; †Sorbonne Universités, Universitè Pierre and Marie Curie University, Paris 06, Paris, France; ‡Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche UMR_S1155, Paris, France; §Laboratoire d’Immunologie, Pôle de Biologie, Centre | Hospitalier Universitalier de Grenoble, Grenoble, France; Centre de Pathologie Est, Hôpitaux de Lyon, Bron, France; BRIEF COMMUNICATION ¶Département de Biochimie Pharmacologie, Biochimie et Génétique Moléculaire, Université de Grenoble Alpes Grenoble, France; and **Assistance Publique-Hôpitaux de Paris, Néphrologie et Dialyses, Hôpital Tenon, Paris, France

ABSTRACT Most patients with idiopathic membranous nephropathy (IMN) have IgG4 autoan- pathway. The concomitant presence of tibodies against phospholipase A2 receptor (PLA2R). C3 and C5b-9 are found in IgG1, especially in early immune deposits, immune deposits of IMN kidney biopsy specimens, but the pathway of complement could possibly be responsible for classic activation in IMN remains elusive. We report the case of a patient who developed pathway activation.9 However, most pa- IMN with intense staining for PLA2R, IgG4, C3, C5b-9, factor B, and properdin and tients with IMN have very weak or unde- very weak staining for C1q, C4d, and IgG1. Measurement of mannan binding lectin tectable C1q deposits. These observations (MBL) antigenic level and activity revealed MBL deficiency. Genotyping revealed a suggest that the alternative and/or lectin heterozygous (A/C) polymorphism in codon 57 of MBL2 exon 1 associated with pathways might be predominantly in- homozygous and heterozygous variations in the promoter region at 2550 (L/L) volved in complement activation and for- and 2221 (X/Y), respectively, suggesting that the patient harbored the LXA/LYC mation of the C5b-9 complex. The first haplotypes linked to MBL deficiency. Genetic sequencing in 77 consecutive patients case series of MBL deficiency reported be- with IMN identified four patients with MBL2 promoter and coding region variations low emphasizes the role of alternative associated with MBL deficiency and the same complement pattern in immune de- pathway complement activation. posits as the index patient. In contrast, patients with wild-type MBL2 had immune A 25-year-old man was referred be- deposits with intense Cd4 staining. Thus, IMN can develop in patients with complete cause of the fortuitous discovery of pro- MBL deficiency, with complement activated mainly by the alternative pathway, teinuria (2.5 g/d) with normal urinary whereas the lectin pathway is also activated in those with wild-type MBL2. sediment. Serum albumin was 3.8 g/dl; serum cholesterol was 5.78 mmol/L J Am Soc Nephrol 27: 3539–3544, 2016. doi: 10.1681/ASN.2015101155

Received October 21, 2015. Accepted March 16, Membranous nephropathy (MN) is one of podocyte antigens, such as the M-type re- 2016. the most common causes of the nephrotic ceptor for secretory phospholipase A2 2 S.B., H.D., P.R., and C.D.-P. contributed equally to syndrome in adults who are not diabetic, (PLA2R) and in rare cases, the thrombo- this work. accounting for up to one third of biopsy spondin type 1 domain 7A.3 Complement Published online ahead of print. Publication date diagnoses. It can be secondary to various plays an important role, even if mecha- available at www.jasn.org. conditions; however, in 70%–80% of pa- nisms of activation have not been clarified tients, MN is a primary (idiopathic) dis- yet. Experimental models have shown that Correspondence: Dr. Stéphane Bally, Service de Néphrologie Dialyse, Centre Hospitalier Métropole ease, with a peak incidence during the C5b-9, the membrane attack complex of Savoie, Place Lucien Biset, 73000 Chambery, France, fourth and fifth decades of life and a complement, is the major mediator of or Dr. Hanna Debiec, Unité Institut National de la men-to-women ratio of 2–3:1.1 proteinuria.4,5 IMN is characterized by Santé et de la Recherche Médicale, Unité Mixte de Recherche UMR_S1155, Hôpital Tenon, 4 rue de la Recent advances have shown that prevailing IgG4 deposits with usually low Chine, 75020 Paris, France. Email: stephane.bally@ idiopathic membranous nephropathy amounts of IgG1.6–8 IgG4 is unique ch-metropole-savoie.fr or [email protected] – fi (IMN) is a kidney speci c autoimmune among IgG subclasses, because it does Copyright © 2016 by the American Society of disease induced by antibodies specificfor not activate the classic complement Nephrology

J Am Soc Nephrol 27: 3539–3544, 2016 ISSN : 1046-6673/2712-3539 3539 BRIEF COMMUNICATION www.jasn.org

(0.223 g/dl). Renal function was normal, with serum creatinine of 75 mmol/L (0.85 mg/dl; Chronic Kidney Disease Epidemi- ology Collaboration .120 ml/min). Renal ultrasound imaging was unremarkable. Clinical examination was normal, and the BP was 120/60 mmHg. The patient did not report any personal or family history of renal or autoimmune disease, toxic exposure, medication intake, and consan- guinity. However, he mentioned very frequent and severe respiratory tract infections during childhood, which were also reported by his mother. A kidney biopsy was performed. Light microscopy showed 24 permeable glomeruli, with thickening of the glomerular basement membrane and spikes delimit- ing subepithelial deposits. There was no mesangial hypercellularity, extracapillary proliferation, or tubulointerstitial abnor- mality. Glomeruli showed finely granular deposits of IgG (Supplemental Figure 1). Immunofluorescence examination revealed intense staining for PLA2R and IgG4, whereas IgG1 was weak (Figure 1). There was no staining for IgG2 or IgG3. Complement components C3 and C5b-9 were present within the subepithelial de- posit, whereas staining for C1q and C4d was graded as very weak (Figure 1). In addition, factor B and properdin were identified within the subepithelial deposits. Anti-PLA2R antibodies were not detected by ELISA (Euroimmun AG). Search for a secondary cause of MN remained negative throughout evolu- tion. Because of the past history of severe respiratory tract infections, antigenicity and activity of complement components were investigated. Complement hemolytic activity of 50% was normal (83%; normal range =82%–126%). C3 component was mildly decreased at 715 mg/L Figure 1. Detection of PLA2R antigen and characterization of immune deposits in kidney biopsy – (normal range =880 1650 mg/L). Factor specimen of the index patient. (A) Immunofluorescence shows the presence of PLA2R in sub- B and C4 component were normal at 246 epithelial deposits along glomerular capillary loops. Immunostaining for IgG subclasses shows mg/L (normal range =216–504 mg/L) (B) a weak fluorescence for IgG1 and (C) a bright fluorescence for IgG4. Complement compo- and 160 mg/L (normal range =100–400 nents, including (D) C3 and (E) C5b-9, are present along glomerular capillary loops. Note the very mg/L), respectively. Alternative path- weak and segmental staining for (F) C1q and (G) C4d and pseudolinear deposition of (H) factor B way activity was high at 225% (normal and (I) properdin along the capillary wall. The images shown in A and G–Iarefromparaffin range =84%–150%). sections, and those shown in B–F are from cryostat sections. Original magnification, 3400. J Exploration of the lectin pathway illustrates the three different pathways of complement activation. The very weak staining for fi revealed a severe quantitative and func- IgG1, C1q, and C4d and the absence of IgG2 and IgG3 deposits argue against signi cant activation of the classic and MBL pathways. The staining for factor B and properdin favors activation tional mannan binding lectin (MBL) of the alternative pathway. AP, alternative pathway; MASP1, MBL–associated serine protease 1. deficiency. MBL antigen level assayed

3540 Journal of the American Society of Nephrology J Am Soc Nephrol 27: 3539–3544, 2016 www.jasn.org BRIEF COMMUNICATION by ELISA10 was low (12 mg/L; normal range =30–3000 mg/L). MBL activity measured by C4 cleavage through the MBL pathway11 was undetectable at ,10% (normal range =35%–135%). MBL deficiency was also found in the patient’sparents.Genotypingofthe polymorphic sites 52, 54, and 57 in the coding sequence of MBL2,thegene coding for MBL, revealed a 57 (A/C) heterozygous polymorphism in codon 57 of exon 1. This structural variant was associated with homozygous and heterozygous variations in the promoter region at 2550 (L/L) and 2221 (X/Y), respec- tively12 (Figure 2). No mutation was observed in codons 52 and 54. On the basis of the different haplotypes described by Garred et al.,13 our patient likely harbors the LXA/LYC haplotypes, which have been associated with MBL deficiency. The father has the same genotype as his son. The mother bears a 54 (A/B) heterozygous polymorphism in exon 1 (no mutation was observed for 52 and 57 codons) and homozygous and heterozygous variations in the promoter region at 2550 (L/L) and 2221 (X/Y), respectively, defining the LXA/LYB haplotype. These results led us to sequence the MBL2 gene in 77 consecutive patients with IMN. We found two patients harboring the LYC/LYC haplotype and the LYB/LYB haplotype, respectively, and two patients with compound heterozygous mutations reveal- ing the already–described haplotypes LYB/ LYC and HYD/LYB (Figure 2). These ge- notypes have been shown to be associated with MBL deficiency.13 These four patients had typical nephrotic PLA2R– related IMN with predominance of IgG4 and very weak or absent IgG1 and C1q in Figure 2. MBL genetic study. (A) Schematic representation of the major MBL2 isoform and the immune deposits. As observed in genetic polymorphism. (B) The chromatogram is represented for two MBL2 promoter our index patient, all patients with mu- single–nucleotide polymorphisms (rs11003125 and rs7096206) and the MBL2 exon 1 tations associated with MBL deficiency structural variant (rs1800451). Gray letters indicate heterozygous variant with S (C or G also had weak and segmental staining nucleotides) and R (G or A nucleotides). (C) Single-nucleotide polymorphisms in promotor for C4d. In contrast, in patients without and exon 1 structural variants detected in four of 77 patients with IMN. Note that two patients were homozygous for the LYB and LYC haplotypes, respectively, whereas two mutations in the MBL2 gene, Cd4 was additional patients were compound heterozygous, bearing the HYD/LYB and LYB/LYC very well visible in the immune deposits haplotypes, respectively. The MBL allele classic nomenclature is shown in column 5. (Figure 3). In contrast, properdin was de- dbSNP, single nucleotide polymorphism database. tected in both groups of patients with MN independent of MBL status. Taken together, these data suggest that, in pathway, whereas in those with a wild– We report the first case of IMN in a patients with MBL deficiency, comple- type MBL2 gene, both the alternative and patient with MBL deficiency, which led ment is activated mainly by alternative lectin pathways are activated. us to investigate a series of 77 consecutive

J Am Soc Nephrol 27: 3539–3544, 2016 Membranous Nephropathy and Mannan Binding Lectin 3541 BRIEF COMMUNICATION www.jasn.org

polymorphisms in MBL2. These variants are mostly located in exon 1 and the promoter region.17,18 MBL deficiency is associated with increased frequency of respiratory tract infections, mostly oc- curring during childhood. It seems rarely symptomatic in adults, probably compensated for by other mechanisms of recognition and activation of complement,19–22 although susceptibility to infections could be increased by immu- nosuppressants.23,24 As yet, we have only used antiproteinuric treatment in our patient, but increased susceptibility to infections will be carefully considered if immunosuppressive therapy is needed. Our patient, with a history of repeated and severe respiratory tract infections during childhood, harbors the genotype A/C, which is associated with two other single–nucleotide polymorphism variants in the promoter region. This geno- typic profile has been associated with severe MBL deficiency.13 This patient also developed PLA2R-related IMN. The bright PLA2R staining in subepithelial deposits, the large predominance of IgG4, and the absence of secondary cause were strongly in favor of a primary Figure 3. Characterization of immune deposits in kidney biopsy specimens from patients form. The absence of circulating anti- with PLA2R-related IMN with or without MBL deficiency. (A) Weak and segmental staining body might be because of low titers un- fi for C4d is observed in four patients with MBL de ciency. (B) In contrast, in patients without der the detection limit of the technique mutations in the MBL2 gene, C4d is well visible in granular deposits along the glomerular decreasing activity of the disease or rapid capillary wall. (C and D) Properdin is detected in both groups of patients with IMN in- clearance of antibodies with high affinity dependent of MBL status. Paraffin sections are shown. Original magnification, 3400. for the target.25,26 These five patients offer a unique op- patients with IMN, where we found four pathways: the classic pathway, the alter- portunity to dissect the mechanisms of additional patients with sequence poly- native pathway, and the lectin pathway, complement activation in IMN. Recent morphisms in the promoter and the which all lead to cleavage of C3 and emphasis has been put on the MBL path- coding region known to be associated activation of the common terminal pathway for three reasons. First, C4 and C4d with MBL deficiency.13 The cases in these way, with generation of the membrane deposits contrasting with the usual absence patients strongly suggest that terminal attack complex C5b-9 and release of of C1q favor MBL pathway activation. complement activation can occur in anaphylatoxins C3a and C5a. Second, MBL has been identified in the the absence of activation of the MBL The lectin pathway is activated by glomeruli of many patients with IMN.4,8,27 pathway. Because the classic pathway interaction between MBL or ficolins and Third, MBL binds terminal residues typi- was not or only minimally activated various nonself-oligosaccharides. MBL cally limited to microbial carbohydrates (very weak deposits of C1q and C4d), binds, in particular, to mannose or and apoptotic host cells.28 However, this observation highlights the pivotal N-acetyl-glucosamine and reacts with whentheFcglycanofIgGterminates role of the alternative pathway in the the MBL–associated serine proteases, with a N-acetyl-D-glucosamine, residue, pathogenesis of IMN, at least in a sub- leading to cleavage of C4 and C2 and MBL can bind to IgG and activate the lec- population of patients. formation of C3 convertase.14,15 MBL tin pathway.29 Increased levels of the The complement system plays a key deficiency, which seems to be the most agalactosyl IgG-G0 glycoform, termi- role in defense against pathogens and common deficiency in complement, be- nating in N-acetyl-D-glucosamine, have regulation of immune homeostasis. ing detected in 10%–15% of whites,16 been reported in patients with autoim- Complement may be activated by three has been attributed to single-nucleotide mune diseases.4,30,31

3542 Journal of the American Society of Nephrology J Am Soc Nephrol 27: 3539–3544, 2016 www.jasn.org BRIEF COMMUNICATION

In patients with MBL deficiency and Staining for PLA2R, C4d, factor B, and 2. Beck LH Jr., Bonegio RG, Lambeau G, Beck IMN, alternative pathway of comple- properdinwas performed on paraffinsections DM, Powell DW, Cummins TD, Klein JB, Salant DJ: M-type phospholipase A2 re- using rabbit polyclonal to human PLA2R ment plays the leading role, although ceptor as target antigen in idiopathic mem- the weak presence of C4d might still be (Atlas Antibodies), rabbit monoclonal to branous nephropathy. NEnglJMed361: the consequence of a low level of activa- human C4d (DB BIOTECH) and human 11–21, 2009 tion ofthe classicpathwayor activation of factor B (Quidel), and rabbit polyclonal to 3. Tomas NM, Beck LH Jr., Meyer-Schwesinger the MBL–associated serine proteases human properdin (Biorbyt) as primary C, Seitz-Polski B, Ma H, Zahner G, Dolla G, Hoxha E, Helmchen U, Dabert-Gay AS, antibodies. through an MBL-independent mecha- Debayle D, Merchant M, Klein J, Salant DJ, nism. Activation of the alternative path- Stahl RA, Lambeau G: Thrombospondin way is a physiologic process that is Complement Analyses type-1 domain-containing 7A in idiopathic controlled by complement regulatory Proteins were quantified by nephelometry membranous nephropathy. N Engl J Med 371: 2277–2287, 2014 proteins (CRPs), such as factor H. The (BN2Simens). Complement hemolytic activ- 4. Ma H, Sandor DG, Beck LH Jr.: The role of mechanisms of hyperactivation of the al- ity (50%) was measured by hemolytic spec- complement in membranous nephropathy. ternative pathway in IMN are unclear. In trophotometric assay using sheep and rabbit Semin Nephrol 33: 531–542, 2013 Heymann nephritis, antibodies to CRPs erythrocytes for classical and alternative path- 5. Debiec H, Ronco P: Immunopathogenesis have been identified.32 In human IMN, way, respectively. MBL concentration was of membranous nephropathy: An update. Semin Immunopathol 36: 381–397, 2014 functional polymorphisms of CRPs, assayed with homemade ELISA.10 MBL activ- 6. Kuroki A, Shibata T, Honda H, Totsuka D, such as those described in IgA nephrop- ity was measured from C4 cleavage through Kobayashi K, Sugisaki T: Glomerular and se- 33 athy, might be at play. In addition, the MBL pathway to activation by mannan as rum IgG subclasses in diffuse proliferative anti-PLA2R IgG4 may damage podo- described by Dumestre-Perard et al.11 lupus nephritis, membranous lupus nephritis, cytes on direct interaction with PLA2 re- MBL activity was measured from C4 and idiopathic membranous nephropathy. Intern Med 41: 936–942, 2002 ceptor function, and in turn, damaged cleavage following MBL pathway activation 7. Ohtani H, Wakui H, Komatsuda A, Okuyama et al podocytes could accelerate activation of as described by Dumestre-Perard .inref- S, Masai R, Maki N, Kigawa A, Sawada K, Imai alternative pathway. erence 11. Different haplotypes in the promoter H: Distribution of glomerular IgG subclass This case series highlights the role region of the MBL2 gene were determined as deposits in malignancy-associated membra- of the alternative pathway of comple- described by Steffensen et al.12 nous nephropathy. Nephrol Dial Transplant 19: 574–579, 2004 ment in IMN pathogenesis. It does not Sequencing of the MBL2 gene was per- 8. Segawa Y, Hisano S, Matsushita M, Fujita T, fi – – exclude a speci c effect of anti-PLA2R formed by capture based high coverage Hirose S, Takeshita M, Iwasaki H: IgG IgG4. Additional studies are needed to next generation sequencing. subclasses and complement pathway in investigate these mechanisms and the segmental and global membranous ne- prevalence of MBL deficiency and CRP phropathy. Pediatr Nephrol 25: 1091–1099, polymorphisms in patients with IMN. 2010 ACKNOWLEDGMENTS 9. Huang CC, Lehman A, Albawardi A, Satoskar A, Brodsky S, Nadasdy G, Hebert L, Rovin B, Nadasdy T: IgG subclass staining in renal bi- ’ CONCISE METHODS The authors research is supported by European opsies with membranous glomerulonephritis Research Council ERC-2012 ADG_20120314 indicates subclass switch during disease pro- – Investigations on patient material were per- grant 322947, Agence Nationale pour la Re- gression. Mod Pathol 26: 799 805, 2013 cherche ANR-Programme Blanc SVSE1 (2012) 10. Dumestre-Pérard C, Ponard D, Drouet C, formed after signature of an informed con- Leroy V, Zarski JP, Dutertre N, Colomb MG: sent by the patients according to French grant ANR-12-BSE1-0002-01, Fondation pour Complement C4 monitoring in the follow-up regulations. la Recherche Médicale grant Equipe FRM 2012, of chronic hepatitis C treatment. Clin Exp and 7th Framework Programme of the European Immunol 127: 131–136, 2002 11. Dumestre-Perard C, Ponard D, Arlaud GJ, Analyses of Kidney Biopsy Community contract 2012-305608 (European Consortium for High-Throughput Research in Monnier N, Sim RB, Colomb MG: Evaluation Specimen and clinical interest of mannan binding lectin ’ The patient s biopsy specimen was prepared Rare Kidney Diseases). function in human plasma. Mol Immunol 39: for light and immunofluorescence micros- 465–473, 2002 copy using standard techniques. For detec- 12. Steffensen R, Thiel S, Varming K, Jersild C, tion of IgG subclasses and complement DISCLOSURES Jensenius JC: Detection of structural gene mutations and promoter polymorphisms in None. components, cryosections of biopsy speci- the mannan-binding lectin (MBL) gene by mens were incubated with the following an- polymerase chain reaction with sequence- tibodies: mouse monoclonal anti–human specific primers. J Immunol Methods 241: REFERENCES IgG1, IgG2, IgG3, and IgG4 (clone HP; 33–42, 2000 Southern Biotech); rabbit polyclonal anti– 13. Garred P, Larsen F, Madsen HO, Koch C: fi – – 1. Ronco P, Debiec H: Pathophysiological ad- Mannose-binding lectin de ciency revisited. human C1q (Dako); anti human C3 comple- vances in membranous nephropathy: Time Mol Immunol 40: 73–84, 2003 – ment (Dako); and monoclonal anti human for a shift in patient’scare.Lancet 385: 1983– 14. Dommett RM, Klein N, Turner MW: Mannose- C5b-9 (Dako). 1992, 2015 binding lectin in innate immunity: Past,

J Am Soc Nephrol 27: 3539–3544, 2016 Membranous Nephropathy and Mannan Binding Lectin 3543 BRIEF COMMUNICATION www.jasn.org

present and future. Tissue Antigens 68: 193– Faber-Krol MC, Madsen HO, Schwaeble WJ, 29. Malhotra R, Wormald MR, Rudd PM, Fischer 209, 2006 Matsushita M, Fujita T, Daha MR: Antibody- PB, Dwek RA, Sim RB: Glycosylation changes 15. Petersen SV, Thiel S, Jensenius JC: The mediated activation of the classical path- of IgG associated with rheumatoid arthritis mannan-binding lectin pathway of comple- way of complement may compensate for can activate complement via the mannose- ment activation: Biology and disease asso- mannose-binding lectin deficiency. Eur J Im- binding protein. Nat Med 1: 237–243, 1995 ciation. Mol Immunol 38: 133–149, 2001 munol 34: 2589–2598, 2004 30. Bond A, Alavi A, Axford JS, Bourke BE, 16. Thiel S, Frederiksen PD, Jensenius JC: Clini- 23. Peterslund NA, Koch C, Jensenius JC, Thiel Bruckner FE, Kerr MA, Maxwell JD, Tweed cal manifestations of mannan-binding lectin S: Association between deficiency of mannose- KJ, Weldon MJ, Youinou P, Hay FC: A de- deficiency. Mol Immunol 43: 86–96, 2006 binding lectin and severe infections after tailed lectin analysis of IgG glycosylation, 17. Turner MW: The role of mannose-binding chemotherapy. Lancet 358: 637–638, demonstrating disease specificchangesin lectin in health and disease. Mol Immunol 40: 2001 terminal galactose and N-acetylglucosamine. 423–429, 2003 24. Bouwman LH, Roos A, Terpstra OT, de Knijff JAutoimmun10: 77–85, 1997 18. Ezekowitz RA: Genetic heterogeneity of P, van Hoek B, Verspaget HW, Berger SP, 31. Parekh R, Isenberg D, Rook G, Roitt I, Dwek mannose-binding proteins: The Jekyll and Daha MR, Frölich M, van der Slik AR, Doxiadis R, Rademacher T: A comparative analysis of Hyde of innate immunity? Am J Hum Genet II, Roep BO, Schaapherder AF: Mannose disease-associated changes in the galac- 62: 6–9, 1998 binding lectin gene polymorphisms confer a tosylation of serum IgG. J Autoimmun 2: 101– 19. SummerfieldJA,RyderS,SumiyaM,Thursz major risk for severe infections after liver 114, 1989 M, Gorchein A, Monteil MA, Turner MW: transplantation. Gastroenterology 129: 408– 32. Schiller B, He C, Salant DJ, Lim A, Alexander Mannose binding protein gene mutations 414, 2005 JJ, Quigg RJ: Inhibition of complement associated with unusual and severe infec- 25. Debiec H, Ronco P: PLA2R autoantibodies regulation is key to the pathogenesis of ac- tions in adults. Lancet 345: 886–889, 1995 and PLA2R glomerular deposits in membra- tive Heymann nephritis. JExpMed188: 20. Garred P, Madsen HO, Hofmann B, nous nephropathy. NEnglJMed364: 689– 1353–1358, 1998 Svejgaard A: Increased frequency of homo- 690, 2011 33. Zhu L, Zhai YL, Wang FM, Hou P, Lv JC, Xu zygosity of abnormal mannan-binding- 26. Fresquet M, Jowitt TA, Gummadova J, DM, Shi SF, Liu LJ, Yu F, Zhao MH, Novak J, protein alleles in patients with suspected Collins R, O’Cualain R, McKenzie EA, Lennon Gharavi AG, Zhang H: Variants in comple- immunodeficiency. Lancet 346: 941–943, R, Brenchley PE: Identification of a major ment factor H and complement factor H- 1995 epitope recognized by PLA2R autoanti- related protein genes, CFHR3 and CFHR1, 21. Koch A, Melbye M, Sørensen P, Homøe P, bodies in primary membranous nephropa- affect complement activation in IgA ne- MadsenHO,MølbakK,HansenCH, thy. J Am Soc Nephrol 26: 302–313, 2015 phropathy. JAmSocNephrol26: 1195– Andersen LH, Hahn GW, Garred P: Acute 27. Lhotta K, Würzner R, König P: Glomerular 1204, 2015 respiratory tract infections and mannose- deposition of mannose-binding lectin in binding lectin insufficiency during early human glomerulonephritis. Nephrol Dial childhood. JAMA 285: 1316–1321, 2001 Transplant 14: 881–886, 1999 22. Roos A, Garred P, Wildenberg ME, Lynch NJ, 28. Thiel S, Gadjeva M: Humoral pattern recog- This article contains supplemental material online Munoz JR, Zuiverloon TC, Bouwman LH, nition molecules: Mannan-binding lectin and at http://jasn.asnjournals.org/lookup/suppl/doi:10. Schlagwein N, Fallaux van den Houten FC, ficolins. Adv Exp Med Biol 653: 58–73, 2009 1681/ASN.2015101155/-/DCSupplemental.

3544 Journal of the American Society of Nephrology J Am Soc Nephrol 27: 3539–3544, 2016