THU0637 Evaluations of complement pathways in igg4 related disease. (12th June 2018)

• Record Type: Journal Article
• Authors: Fukui, S.; Fujita, Y.; Origuchi, T.; Kawakami, A.
• Is Part Of: Annals of the rheumatic diseases. Volume 77(2018)Supplement 2
• Page Start: 514
• Page End: 514
• Publication Date: 2018-06-12
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2018-eular.5029
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: In IgG4 related disease (IgG4-RD), hypocomplementemia is known to be seen. Complement pathways consist of three pathways, classical, alternative, and lectin pathways. Although IgG1 and IgG3 have ability to activate complement, IgG4 is known to be ineffective at activating complement. Objectives: We attempted to elucidate which complement pathway is mainly associated with IgG4-RD. Methods: Levels of complement elements and complement-associated elements, C1q, C2, C3, C3b/iC3b, C4, C4b, C5, C5a, C9, Factor D, Factor I, mannose-binding lectin (MBL), Factor B, Factor H, and properdin in preserved sera of patients with IgG4-RD at diagnosis and at remission were measured using multiplex bead-based assay. We compared complement levels at diagnosis of IgG4RD patients with those of sex-matched healthy donors. Results: This study included 28 IgG4-RD patients and sex-matched 28 healthy donors. The median age at diagnosis and healthy donors' age were 65 [interquartile range (IQR): 55–70] and 64 (IQR:56–73), respectively. Patients with IgG4-RD at diagnosis had significantly higher levels of C5 and C5a [33347 ng/mL vs. 30375 ng/mL (median), p=0.0293, 16417 pg/mL vs. 7083 pg/mL, p<0.0001, respectively] and significantly lower levels of C4, C4b, and Factor D (219671 ng/mL vs. 325596 ng/mL, p=0.0140, 8784 ng/mL vs. 16285 ng/mL, p=0.0101, 4569 ng/mL vs. 5482 ng/mL, p=0.0299, respectively) compared to healthy donors. Levels of C5, C5a, C4, C4b, and Factor D were not different in two groups which were divided by clinical manifestations at diagnosis except for lower C4b levels in patients with lymphadenopathy compared with patients without lymphadenopathy. There were no differences in MBL, which was associated with the lectin pathway. In remission after the administrations of prednisolone, levels of C5a significantly decreased compared to levels of C5a at diagnosis (16305 pg/mL to 10029 pg/mL, p=0.0043). Other complement factors did not change significantly. Conclusions: The classical complement pathway may be associated with IgG4-RD rather than the alternative pathway and the lectin pathway based on results except for Factor D. Disclosure of Interest: None declared