title: Autoimmune severe hypertriglyceridemia induced by anti-apolipoprotein C-II antibody.
abstract: BACKGROUND
  Among type V hyperlipoproteinemias, only one-fourth of the patients have genetic defects in lipoprotein lipase (LPL) or in its associated molecules; the exact mechanism in other patients is usually unknown.
  
  
  OBJECTIVE
  The aim of the study was to report a case of severe hypertriglyceridemia induced by anti-apolipoprotein (apo) C-II autoantibody and to clarify its pathogenesis.
  
  
  METHODS
  A 29-year-old Japanese woman presented with severe persistent hypertriglyceridemia since the age of 20 years. The past history was negative for acute pancreatitis, eruptive xanthomas, or lipemia retinalis. LPL mass and activities were normal. Plasma apo C-II levels were extremely low, but no mutation was observed in APOC2.
  
  
  RESULTS
  Apo C-II protein was detected in the serum by immunoprecipitation and Western blotting. Large amounts of IgG and IgM were incorporated with apo C-II protein coimmunoprecipitated by anti-apo C-II antibody. IgG, but not IgM, purified from the serum prevented interaction of apo C-II with lipid substrate and diminished LPL hydrolysis activity.
  
  
  CONCLUSIONS
  We identified anti-apo C-II antibody in a myeloma-unrelated severe hypertriglyceridemic patient. In vitro analysis confirmed that the autoantibody disrupted the interaction between apo C-II and lipid substrate, suggesting the etiological role of anti-apo C-II antibody in severe hypertriglyceridemia in this patient.
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences (H.Y., M.T., S.Y., S.K.), and Department of Metabolic Medicine (T.F., I.S.), Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanaka
authors.forename: Satomi
authors.initials: S
authors.lastname: Yoshiga
authors.forename: Tohru
authors.initials: T
authors.lastname: Funahashi
authors.forename: Iichiro
authors.initials: I
authors.lastname: Shimomura
authors.forename: Shinji
authors.initials: S
authors.lastname: Kihara
mesh_terms: D000328:Adult; D053304:Apolipoprotein C-II / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood / Q000276:immunology*; D005260:Female; D006801:Humans; D015228:Hypertriglyceridemia / Q000097:blood / Q000276:immunology*
chemical_list: D053304:Apolipoprotein C-II; D001323:Autoantibodies; C054300:apolipoprotein C-II (St Michael)