title: Autoantibodies against a complement component 1 q subcomponent contribute to complement activation and recurrent thrombosis/pregnancy morbidity in anti-phospholipid syndrome.
abstract: To investigate the prevalence and significance of the autoantibodies against complement component 1 q subcomponent (C1q) in patients with APS.
  
  
  
  In all, 40 consecutive primary APS patients, 42 patients with non-SLE CTDs and 20 SLE patients negative for aPL were enrolled in this retrospective analysis. Refractory APS was defined as a clinical status of recurring thrombosis or pregnancy morbidity during adequate secondary prophylaxis. An ELISA was used to measure serum levels of anti-C1q antibodies and anaphylatoxins (C3a, C4a).
  
  
  
  Anti-C1q antibodies were found in 36% (15/42) and 2.5% (1/40) of primary APS patients and controls, respectively. Among primary APS patients, anti-C1q antibody titres were significantly correlated with serum C4a levels (P = 0.013). Neither the prevalence nor the titre of anti-C1q antibodies was associated with any specific clinical manifestations of APS, nor titres of aPL. Refractory APS patients (n = 10) had a higher prevalence of anti-C1q antibodies (9/10 vs 6/32, P = 0.01) than APS patients without recurrence (n = 32).
  
  
  
  Anti-C1q antibodies are associated with complement activation in APS and may contribute to the pathogenesis, particularly in refractory cases.
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan kenoku@med.hokudai.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Oku
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Olga
authors.initials: O
authors.lastname: Amengual
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Hisada
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Ohmura
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Ikuma
authors.initials: I
authors.lastname: Nakagawa
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Bohgaki
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Horita
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Yasuda
authors.affiliation: Department of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Atsumi
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D017152:Antibodies, Antiphospholipid / Q000502:physiology*; D016736:Antiphospholipid Syndrome / Q000276:immunology*; D003167:Complement Activation / Q000502:physiology; D015922:Complement C1q / Q000276:immunology*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology; D012008:Recurrence; D012189:Retrospective Studies; D013927:Thrombosis / Q000276:immunology*; D055815:Young Adult
chemical_list: D017152:Antibodies, Antiphospholipid; D015922:Complement C1q
keywords: anti-C1q antibodies; anti-phospholipid syndrome; complement activation