Autoantibody-mediated arthritis in the absence of C3 and activating Fcγ receptors: C5 is activated by the coagulation cascade
© Auger et al.; licensee BioMed Central Ltd. 2012
Received: 30 October 2012
Accepted: 11 December 2012
Published: 13 December 2012
The effector functions of immunoglobulin G (IgG) are mediated by interaction of its Fc region with Fc receptors (FcγRs) and/or the complement system. The three main pathways of complement activation converge at C3. However, C3-independent pathways can activate C5 and other downstream complement components during IgG-initiated inflammatory responses. These C3-independent pathways of C5 activation are triggered by activating FcγRs in some systems or can be activated by factors of the coagulation cascade such as thrombin. Here we studied the interplay of C3, C5, and activating FcγRs in a model of spontaneous autoantibody-driven arthritis.
We utilized the K/BxN TCR transgenic mouse model of arthritis. We bred K/BxN mice bearing targeted or naturally-occurring mutations in one or more of the genes encoding complement components C3, C5, and FcRγ, the cytoplasmic signaling chain shared by the activating FcγRs. We measured arthritis development, the production of arthritogenic autoantibodies, T cell activation status and cytokine synthesis. In addition, we treated mice with anti-C5 monoclonal antibodies or with the thrombin inhibitor argatroban.
We have previously shown that genetic deficiency of C5 protects K/BxN mice from the development of arthritis. We found here that C3-deficient K/BxN mice developed arthritis equivalent in severity to C3-sufficient animals. Arthritis also developed normally in K/BxN mice lacking both C3 and FcRγ, but could be ameliorated in these animals by treatment with anti-C5 monoclonal antibody or by treatment with argatroban. Production of arthritogenic autoantibodies, T cell activation, and T cell cytokine production were not affected by the absence of C3, C5, and/or FcRγ.
In K/BxN mice, C5-dependent autoantibody-driven arthritis can occur in the genetic absence of both complement C3 and activating FcγRs. Our findings suggest that in this setting, thrombin activates C5 to provoke arthritis.
The ability of immunoglobulin and immune complexes, including autoantibodies, to provoke inflammation stems from the interaction of the Fc portion of antibody molecules with one or both of two major effector pathways: Fc receptors and the complement system. The relative contributions of these two pathways vary among different disease states and experimental systems [1–3]. A more detailed understanding of the mechanisms by which autoantibodies engage Fc receptors and complement to provoke pathology in a specific target tissue can permit a more tailored therapeutic intervention.
Fcγ receptors (FcγRs) recognize immunoglobulin G (IgG) and transduce either activating or inhibitory intracellular signals. In the mouse, the activating FcγRs include FcγRI, FcγRIII, and FcγRIV. The activating FcγRs share a common cytoplasmic signaling chain called FcRγ (encoded by the Fcer1g gene) responsible for signal transduction. Mice also express the inhibitory receptor FcγRIIB, whose cytoplasmic tail contains an inhibitory signaling motif. The outcome of an interaction of an FcγR-expressing cell with an IgG-containing immune complex depends on the relative expression levels of the various activating and inhibitory FcγRs and also the IgG subtype (for which the various FcγRs have differing affinities) .
Several studies have pointed to the existence of additional, C3-independent mechanisms by which C5 can be activated to drive inflammatory responses (Figure 1). More than two decades ago, investigators described the existence of C5-C9-dependent immune hemolysis occurring in a C3-independent fashion [7, 8]. More recently, studies of IgG-triggered acute lung injury revealed that, in C3-deficient mice, thrombin can act as a C5 convertase to generate C5a and mediate pathology . Similar crosstalk between the complement system and coagulation systems has been identified in other model systems, including antiphospholipid antibody-induced and lipopolysaccharide (LPS)-induced fetal loss in mice [10, 11]. An elegant in vitro study has recently confirmed that multiple serine proteases in the coagulation and fibrinolysis systems can cleave C3 and C5 to produce C3a and C5a . Interplay of FcγRs and the complement system also occurs, and several studies of IgG-initiated pathology have highlighted the existence of a C5a generation pathway that is triggered by activating FcγRs [2, 13–15]. Here, we investigated a possible contribution of C3-independent mechanisms of C5 activation in a mouse model of autoantibody-mediated arthritis.
K/BxN T-cell receptor (TCR) transgenic mice spontaneously develop inflammatory arthritis due to combined T- and B-cell recognition of the self-antigen glucose-6-phosphate isomerase (GPI) and production of high-titer anti-GPI IgG autoantibodies [16, 17]. Arthritis can also be provoked by injecting serum from K/BxN mice into normal mice . Importantly, the requirements for complement and activating FcγRs differ between the K/BxN TCR transgenic mice and its derivative, the serum transfer model, likely reflecting the several-fold higher concentration of anti-GPI autoantibodies in the spontaneous genetic model. The development of serum-transferred arthritis depends on both activating FcγRs and the alternative pathway of complement activation. Specifically, mice with targeted or naturally occurring mutations in the genes encoding factor B (of the alternative pathway), C3, C5, the C5a receptor (C5aR), and FcRγ were protected from developing serum-transferred arthritis [19–21]. In contrast, we have shown that K/BxN TCR transgenic mice lacking FcRγ developed spontaneous arthritis equivalently to controls but that C5-deficient K/BxN mice developed less severe arthritis than controls . In addition, treating K/BxN mice with anti-C5 monoclonal antibody reduced their arthritis severity . Those findings led us to investigate which of the upstream C5-activation pathways drives arthritis in K/BxN mice.
Materials and methods
KRN TCR transgenic mice on the C57BL/6 (B6) background  were a gift from Diane Mathis and Christophe Benoist (Harvard Medical School, Boston, MA, USA) and the Institut de Génétique et de Biologie Moléculaire et Cellulaire (Strasbourg, France). C5-deficient B6 mice congenic for the non-obese diabetic (NOD)-derived Hc allele (encoding non-functional C5) [22, 23] and B6 mice congenic for H-2g7 (B6.g7) were also a gift from Mathis and Benoist; I-Ag7 is the mouse major histocompatibility complex (MHC) class II molecule that presents GPI-derived peptides to activate KRN TCR-expressing T cells. C3-deficient mice on the B6 background  were a gift from Michael Carroll (Harvard Medical School). FcRγ (Fcer1g)-deficient mice on the B6 background  were purchased from Taconic (Hudson, NY, USA).
The C3-, C5-, FcRγ-, and double-deficient 'K/BxN' lines used in this study were created by breeding mice bearing the appropriate knockout allele(s) on the B6 background to KRN/B6 mice and also to B6.g7 congenic mice. The MHC (H2) is the only NOD-derived genetic region that the B6.g7 mice retain; to simplify nomenclature, however, we refer to the mice as 'K/BxN' throughout this study as we have previously . Because C3 and the H2 complex both reside on mouse chromosome 17, a spontaneous chromosomal recombination event was necessary to generate C3-deficient B6.g7 congenic mice. Genotyping of mice was performed by standard polymerase chain reactions. Mice were bred in specific pathogen-free colonies under protocols approved by the University of Minnesota Institutional Animal Care and Use Committee.
Anti-C5 monoclonal antibodies were derived from the BB5.1 hybridoma, a gift from Brigitta Stockinger (MRC National Institute for Medical Research, London, UK) . Antibodies used for flow cytometry included anti-CD3 (clone 71A2), anti-CD44 (clone IM7), anti-CD62L (clone MEL-14), anti-interleukin-17 (anti-IL-17) (clone eBiol7B7), and anti-interferon-gamma (anti-IFNγ) (clone XMG1.2) from eBioscience (San Diego, CA, USA) and anti-CD4 (clone RM4-5) and anti-Vβ6 (clone RR4-7) from BD Pharmingen (San Diego, CA, USA).
Assessment of arthritis, anti-C5 antibody treatment, anti-GPI titers, histology, and immunohistochemistry
Assessment of arthritis severity by clinical score and ankle thickening, treatment with anti-C5 antibody, determination of anti-GPI IgG titers by enzyme-linked immunosorbent assay, histological analysis, and immunohistochemistry for C3 and IgG were performed as described . For detection of prothrombin, histologic sections of mouse liver were first blocked by using the avidin/biotin blocking kit (Invitrogen Corporation, Carlsbad, CA, USA). Primary antibodies then were added at a dilution of 1:20, in accordance with a prior report . The primary antibodies were goat polyclonal IgG anti-thrombin (K20) or normal goat IgG (both from Santa Cruz Biotechnology, Inc., Santa Cruz, CA, USA). The primary antibodies were detected by secondary staining with biotin-coupled donkey anti-goat IgG diluted 1:2,000 (Santa Cruz Biotechnology, Inc.) followed by application of ImmPACT DAB peroxidase substrate with the ABC peroxidase kit (Vector Laboratories, Burlingame, CA, USA).
Intracellular cytokine staining was performed in accordance with the instructions of the manufacturer (eBioscience). Flow cytometry was performed by using a FACSCalibur and an LSRII (BD Biosciences, San Jose, CA, USA), and cells were analyzed by using FlowJo V7.6 software (Tree Star, Inc., Ashland, OR, USA).
Argatroban (Sigma-Aldrich, St. Louis, MO, USA) was dissolved in dimethyl sulfoxide (DMSO) and injected intraperitoneally into mice at a dose of 9 mg/kg daily or five days per week fromthe ages of 3 to 6 weeks [27, 28]. No differences were observed between those mice receiving argatroban daily and those receiving it five days per week, so the results were pooled for analysis. The vehicle control-treated animals received DMSO intraperitoneally.
Results and Discussion
Consistent with our prior report that arthritis in K/BxN mice depends on C5 but not FcRγ , we found that K/BxN mice lacking both C5 and FcRγ developed less severe arthritis than controls (Figure 3b). In the ankles of these C5/FcRγ-deficient K/BxN mice, deposition of both IgG and C3 was detectable, suggesting that C3 deposition can still occur in the absence of C5 and despite the less severe inflammatory response in these joints (Additional file 1b). The fact that the C5/FcRγ-deficient mice developed some arthritis, albeit attenuated, suggests that other minor pathogenic effector mechanisms are still operational in these mice; candidate pathways include recognition of IgG immune complexes by upstream complement components and their receptors (for example, C1qR(P)/CD93 ), the pro-inflammatory activity of C3a , and pathogenic effector T cells.
Whether C3-independent pathways of C5 activation contribute to pathology in wild-type mice or only in the setting of genetic C3 deficiency is important for understanding the relevance of these pathways to human diseases. For instance, heparin was effective in reducing antiphospholipid antibody-induced fetal loss in wild-type mice by blocking C5a generation . Similarly, treatment with the thrombin inhibitor polyethyleneglycol-hirudin (PEG-hirudin) decreased the severity of collagen-induced arthritis in mice, although this was attributed to reductions in intra-articular fibrin deposition rather than to effects on complement activation . In contrast, in the IgG-mediated lung injury model, the effect of the anticoagulants anti-thrombin III and hirduin in reducing lung pathology was evident only in C3-deficient animals, leading those investigators to speculate that genetic deficiency in C3 leads to upregulation of thrombin as a compensatory mechanism to allow C5 activation via a non-traditional pathway . Similarly, we observed no effect of argatroban on arthritis severity in C3-sufficient K/BxN mice (data not shown), but we are currently exploring longer-acting thrombin inhibitors. Thus, the contribution of the coagulation cascade to C5 activation might vary depending on the disease model. In addition, a recent report suggests that, in vitro, thrombin cleaves C5 at a site different from that cleaved by C5 convertase, leading to the generation of novel intermediates . Understanding whether these intermediates are also generated in vivo and, if so, how they affect inflammation will be essential next steps.
How IgG antibodies activate thrombin in the absence of activating FcγRs and C3 remains an open and important question. Since thrombin activation by IgG has been observed in multiple autoantibody-dependent models, it is not likely that the antigenic specificity is critical. It seems more likely that other IgG-interacting molecules (for example, complement C1q or the neonatal Fc receptor) could be at play. Alternatively, antibody fragments with direct prothrombinase catalytic activity have been described .
From a clinical perspective, monoclonal antibody reagents designed to interfere with C5 activation systemically or locally (for example, in the synovium) might be effective treatments for inflammatory arthritis (Figure 3a) [22, 38, 39]. Our findings suggest that agents designed to interfere with non-traditional C5 activation pathways such as the coagulation cascade might also prove beneficial for treating inflammatory arthritis in certain settings.
The key finding of this study is that autoantibody-mediated arthritis in K/BxN mice can occur via a C5 activation pathway that requires neither C3 nor activating FcγRs, the two main effector mechanisms of IgG molecules. Genetic deficiency of C3, C5, and/or FcRγ did not affect T-cell activation or autoantibody production, indicating that the pro-arthritogenic activity of C5 is mediated by its conventional effector mechanisms (likely C5a production). Our data further suggest that thrombin or related proteases of the coagulation cascade mediate C5 activation in the absence of C3 and FcRγ. Understanding how novel pathways of complement activation contribute to autoantibody-mediated arthritis and other inflammatory disorders is expected to lead to new therapeutic approaches.
Fc receptor for immunoglobulin G
the cytoplasmic signaling chain shared by activating Fc receptors for immunoglobulin G
membrane attack complex
major histocompatibility complex
T helper 17.
The studies were supported by K08 AR054317 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (to BAB) and by awards and start-up funds from the University of Minnesota Department of Pediatrics. BAB was supported by an Arthritis Foundation Arthritis Investigator Award. The authors thank Sindhuja Rao for technical assistance and Christophe Benoist, Michael Carroll, Diane Mathis, and Brigitta Stockinger for gifts of mice and reagents.
- Ravetch JV, Clynes RA: Divergent roles for Fc receptors and complement in vivo. Annu Rev Immunol. 1998, 16: 421-432. 10.1146/annurev.immunol.16.1.421.View ArticlePubMedGoogle Scholar
- Baumann U, Kohl J, Tschernig T, Schwerter-Strumpf K, Verbeek JS, Schmidt RE, Gessner JE: A codominant role of Fc gamma RI/III and C5aR in the reverse Arthus reaction. J Immunol. 2000, 164: 1065-1070.View ArticlePubMedGoogle Scholar
- Sylvestre D, Clynes R, Ma M, Warren H, Carroll MC, Ravetch JV: Immunoglobulin G-mediated inflammatory responses develop normally in complement-deficient mice. J Exp Med. 1996, 184: 2385-2392. 10.1084/jem.184.6.2385.PubMed CentralView ArticlePubMedGoogle Scholar
- Nimmerjahn F, Ravetch JV: FcgammaRs in health and disease. Curr Top Microbiol Immunol. 2011, 350: 105-125.PubMedGoogle Scholar
- Walport MJ: Complement. Second of two parts. N Engl J Med. 2001, 344: 1140-1144. 10.1056/NEJM200104123441506.View ArticlePubMedGoogle Scholar
- Walport MJ: Complement. First of two parts. N Engl J Med. 2001, 344: 1058-1066. 10.1056/NEJM200104053441406.View ArticlePubMedGoogle Scholar
- Kitamura H, Matsumoto M, Nagaki K: C3-independent immune haemolysis: haemolysis of EAC14oxy2 cells by C5-C9 without participation of C3. Immunology. 1984, 53: 575-582.PubMed CentralPubMedGoogle Scholar
- Salama A, Bhakdi S, Mueller-Eckhardt C: Evidence suggesting the occurrence of C3-independent intravascular immune hemolysis. Reactive hemolysis in vivo. Transfusion. 1987, 27: 49-53. 10.1046/j.1537-2995.1987.27187121473.x.View ArticlePubMedGoogle Scholar
- Huber-Lang M, Sarma JV, Zetoune FS, Rittirsch D, Neff TA, McGuire SR, Lambris JD, Warner RL, Flierl MA, Hoesel LM, Gebhard F, Younger JG, Drouin SM, Wetsel RA, Ward PA: Generation of C5a in the absence of C3: a new complement activation pathway. Nat Med. 2006, 12: 682-687. 10.1038/nm1419.View ArticlePubMedGoogle Scholar
- Girardi G, Redecha P, Salmon JE: Heparin prevents antiphospholipid antibody-induced fetal loss by inhibiting complement activation. Nat Med. 2004, 10: 1222-1226. 10.1038/nm1121.View ArticlePubMedGoogle Scholar
- Yu G, Sun Y, Foerster K, Manuel J, Molina H, Levy GA, Gorczynski RM, Clark DA: LPS-induced murine abortions require C5 but not C3, and are prevented by upregulating expression of the CD200 tolerance signaling molecule. Am J Reprod Immunol. 2008, 60: 135-140. 10.1111/j.1600-0897.2008.00605.x.View ArticlePubMedGoogle Scholar
- Amara U, Flierl MA, Rittirsch D, Klos A, Chen H, Acker B, Bruckner UB, Nilsson B, Gebhard F, Lambris JD, Huber-Lang M: Molecular intercommunication between the complement and coagulation systems. J Immunol. 2010, 185: 5628-5636. 10.4049/jimmunol.0903678.PubMed CentralView ArticlePubMedGoogle Scholar
- Kumar V, Ali SR, Konrad S, Zwirner J, Verbeek JS, Schmidt RE, Gessner JE: Cell-derived anaphylatoxins as key mediators of antibody-dependent type II autoimmunity in mice. J Clin Invest. 2006, 116: 512-520. 10.1172/JCI25536.PubMed CentralView ArticlePubMedGoogle Scholar
- Syed SN, Konrad S, Wiege K, Nieswandt B, Nimmerjahn F, Schmidt RE, Gessner JE: Both FcgammaRIV and FcgammaRIII are essential receptors mediating type II and type III autoimmune responses via FcRgamma-LAT-dependent generation of C5a. Eur J Immunol. 2009, 39: 3343-3356. 10.1002/eji.200939884.View ArticlePubMedGoogle Scholar
- Baumann U, Chouchakova N, Gewecke B, Kohl J, Carroll MC, Schmidt RE, Gessner JE: Distinct tissue site-specific requirements of mast cells and complement components C3/C5a receptor in IgG immune complex-induced injury of skin and lung. J Immunol. 2001, 167: 1022-1027.View ArticlePubMedGoogle Scholar
- Kouskoff V, Korganow AS, Duchatelle V, Degott C, Benoist C, Mathis D: Organ-specific disease provoked by systemic autoimmunity. Cell. 1996, 87: 811-822. 10.1016/S0092-8674(00)81989-3.View ArticlePubMedGoogle Scholar
- Matsumoto I, Staub A, Benoist C, Mathis D: Arthritis provoked by linked T and B cell recognition of a glycolytic enzyme. Science. 1999, 286: 1732-1735. 10.1126/science.286.5445.1732.View ArticlePubMedGoogle Scholar
- Korganow AS, Ji H, Mangialaio S, Duchatelle V, Pelanda R, Martin T, Degott C, Kikutani H, Rajewsky K, Pasquali JL, Benoist C, Mathis D: From systemic T cell self-reactivity to organ-specific autoimmune disease via immunoglobulins. Immunity. 1999, 10: 451-461. 10.1016/S1074-7613(00)80045-X.View ArticlePubMedGoogle Scholar
- Corr M, Crain B: The role of FcgammaR signaling in the K/B × N serum transfer model of arthritis. J Immunol. 2002, 169: 6604-6609.View ArticlePubMedGoogle Scholar
- Ji H, Ohmura K, Mahmood U, Lee DM, Hofhuis FM, Boackle SA, Takahashi K, Holers VM, Walport M, Gerard C, Ezekowitz A, Carroll MC, Brenner M, Weissleder R, Verbeek JS, Duchatelle V, Degott C, Benoist C, Mathis D: Arthritis critically dependent on innate immune system players. Immunity. 2002, 16: 157-168. 10.1016/S1074-7613(02)00275-3.View ArticlePubMedGoogle Scholar
- Ji H, Gauguier D, Ohmura K, Gonzalez A, Duchatelle V, Danoy P, Garchon HJ, Degott C, Lathrop M, Benoist C, Mathis D: Genetic influences on the end-stage effector phase of arthritis. J Exp Med. 2001, 194: 321-330. 10.1084/jem.194.3.321.PubMed CentralView ArticlePubMedGoogle Scholar
- Binstadt BA, Hebert JL, Ortiz-Lopez A, Bronson R, Benoist C, Mathis D: The same systemic autoimmune disease provokes arthritis and endocarditis via distinct mechanisms. Proc Natl Acad Sci USA. 2009, 106: 16758-16763. 10.1073/pnas.0909132106.PubMed CentralView ArticlePubMedGoogle Scholar
- Wetsel RA, Fleischer DT, Haviland DL: Deficiency of the murine fifth complement component (C5). A 2-base pair gene deletion in a 5'-exon. J Biol Chem. 1990, 265: 2435-2440.PubMedGoogle Scholar
- Wessels MR, Butko P, Ma M, Warren HB, Lage AL, Carroll MC: Studies of group B streptococcal infection in mice deficient in complement component C3 or C4 demonstrate an essential role for complement in both innate and acquired immunity. Proc Natl Acad Sci USA. 1995, 92: 11490-11494. 10.1073/pnas.92.25.11490.PubMed CentralView ArticlePubMedGoogle Scholar
- Takai T, Li M, Sylvestre D, Clynes R, Ravetch JV: FcR gamma chain deletion results in pleiotrophic effector cell defects. Cell. 1994, 76: 519-529. 10.1016/0092-8674(94)90115-5.View ArticlePubMedGoogle Scholar
- Frei Y, Lambris JD, Stockinger B: Generation of a monoclonal antibody to mouse C5 application in an ELISA assay for detection of anti-C5 antibodies. Mol Cell Probes. 1987, 1: 141-149. 10.1016/0890-8508(87)90022-3.View ArticlePubMedGoogle Scholar
- Schulze EB, Hedley BD, Goodale D, Postenka CO, Al-Katib W, Tuck AB, Chambers AF, Allan AL: The thrombin inhibitor Argatroban reduces breast cancer malignancy and metastasis via osteopontin-dependent and osteopontin-independent mechanisms. Breast Cancer Res Treat. 2008, 112: 243-254. 10.1007/s10549-007-9865-4.View ArticlePubMedGoogle Scholar
- Asanuma K, Wakabayashi H, Hayashi T, Okuyama N, Seto M, Matsumine A, Kusuzaki K, Suzuki K, Uchida A: Thrombin inhibitor, argatroban, prevents tumor cell migration and bone metastasis. Oncology. 2004, 67: 166-173. 10.1159/000081004.View ArticlePubMedGoogle Scholar
- Tsao PY, Arora V, Ji MQ, Wright AC, Eisenberg RA: KRN/I-Ag7 mouse arthritis is independent of complement C3. J Clin Immunol. 2011, 31: 857-863. 10.1007/s10875-011-9562-2.PubMed CentralView ArticlePubMedGoogle Scholar
- Kim TS, Park M, Nepomuceno RR, Palmarini G, Winokur S, Cotman CA, Bengtsson U, Tenner AJ: Characterization of the murine homolog of C1qR(P): identical cellular expression pattern, chromosomal location and functional activity of the human and murine C1qR(P). Mol Immunol. 2000, 37: 377-389. 10.1016/S0161-5890(00)00057-2.View ArticlePubMedGoogle Scholar
- Hashimoto M, Hirota K, Yoshitomi H, Maeda S, Teradaira S, Akizuki S, Prieto-Martin P, Nomura T, Sakaguchi N, Kohl J, Heyman B, Takahashi M, Fujita T, Mimori T, Sakaguchi S: Complement drives Th17 cell differentiation and triggers autoimmune arthritis. J Exp Med. 2010, 207: 1135-1143. 10.1084/jem.20092301.PubMed CentralView ArticlePubMedGoogle Scholar
- Jacobs JP, Wu HJ, Benoist C, Mathis D: IL-17-producing T cells can augment autoantibody-induced arthritis. Proc Natl Acad Sci USA. 2009, 106: 21789-21794. 10.1073/pnas.0912152106.PubMed CentralView ArticlePubMedGoogle Scholar
- Wu HJ, Ivanov II, Darce J, Hattori K, Shima T, Umesaki Y, Littman DR, Benoist C, Mathis D: Gut-residing segmented filamentous bacteria drive autoimmune arthritis via T helper 17 cells. Immunity. 2010, 32: 815-827. 10.1016/j.immuni.2010.06.001.PubMed CentralView ArticlePubMedGoogle Scholar
- Foerster K, He W, Manuel J, Bartczak A, Liu M, Markert UR, Levy GA, Clark DA: LPS-induced occult loss in mice requires FGL2. Am J Reprod Immunol. 2007, 58: 524-529. 10.1111/j.1600-0897.2007.00543.x.View ArticlePubMedGoogle Scholar
- Marty I, Peclat V, Kirdaite G, Salvi R, So A, Busso N: Amelioration of collagen-induced arthritis by thrombin inhibition. J Clin Invest. 2001, 107: 631-640. 10.1172/JCI11064.PubMed CentralView ArticlePubMedGoogle Scholar
- Krisinger MJ, Goebeler V, Lu Z, Meixner SC, Myles T, Pryzdial EL, Conway EM: Thrombin generates previously unidentified C5 products that support the terminal complement activation pathway. Blood. 2012, 120: 1717-1725. 10.1182/blood-2012-02-412080.View ArticlePubMedGoogle Scholar
- Thiagarajan P, Dannenbring R, Matsuura K, Tramontano A, Gololobov G, Paul S: Monoclonal antibody light chain with prothrombinase activity. Biochemistry. 2000, 39: 6459-6465. 10.1021/bi992588w.View ArticlePubMedGoogle Scholar
- Woodruff TM, Nandakumar KS, Tedesco F: Inhibiting the C5-C5a receptor axis. Mol Immunol. 2011, 48: 1631-1642. 10.1016/j.molimm.2011.04.014.View ArticlePubMedGoogle Scholar
- Fischetti F, Durigutto P, Macor P, Marzari R, Carretta R, Tedesco F: Selective therapeutic control of C5a and the terminal complement complex by anti-C5 single-chain Fv in an experimental model of antigen-induced arthritis in rats. Arthritis Rheum. 2007, 56: 1187-1197. 10.1002/art.22492.View ArticlePubMedGoogle Scholar
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