title: Prevalence and function of anti-lipoprotein lipase auto-antibodies in type V hyperchylomicronemia.
abstract: OBJECTIVE
  Type V hyperlipidemia (HTG V) characterized by accumulation of both chylomicrons and VLDL results from a complex combination of genetic and environmental factors. However, a large proportion of sporadic cases remains largely unexplained. In a few cases, in a context of autoimmunity, auto-antibodies inhibiting lipoprotein lipase (LPL) activity have been incriminated. To establish their contribution to common type V hyperlipidemia in subjects with no apparent evidence of autoimmune background, we systematically screened the presence of these antibodies and their inhibition properties.
  
  
  METHODS
  Screening for circulating anti-human LPL immunoglobulin G (anti-hLPL IgG) was carried out by western blotting in 63 subjects with HTG V and 77 controls. Inhibition of lipolytic activity by plasma from these patients was measured ex vivo.
  
  
  RESULTS
  Anti-hLPL IgG was detectable in plasma from both controls and subjects with HTG V. After establishment of a threshold value corresponding to the 95th percentile of the control population, 27% of subjects with HTG V were found to have abnormal antibody levels (P<0.001). Only plasma obtained from these hyperchylomicronemic subjects with a high level of anti-hLPL IgG inhibited triglyceride hydrolysis whereas plasma from controls or HTG subjects with normal anti-hLPL IgG levels had no inhibitory effect (-13.5+/-3.4% vs 1.6+/-3.4%; P=0.04). However, no correlation was observed between anti-hLPL IgG levels, inhibitory effect and plasma triglyceride concentration.
  
  
  CONCLUSIONS
  High levels of anti-hLPL immunoreactivity could be detected in only one out of four adult patients with type V hyperchylomicronemia. Furthermore, only a minority of these subjects (less than 10%) displayed both high anti-hLPL IgG levels and substantial inhibition (>20%) of plasma lipolysis. These auto-antibodies, in this setting only, might contribute to the occurrence of a minority of sporadic type V dyslipidemia cases.
authors.forename: Myriam
authors.initials: M
authors.lastname: Moret
authors.forename: Valérie
authors.initials: V
authors.lastname: Pruneta-Deloche
authors.forename: Agnès
authors.initials: A
authors.lastname: Sassolas
authors.forename: Christophe
authors.initials: C
authors.lastname: Marcais
authors.forename: Philippe
authors.initials: P
authors.lastname: Moulin
mesh_terms: D001323:Autoantibodies / Q000737:chemistry*; D015551:Autoimmunity; D015153:Blotting, Western; D002914:Chylomicrons / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D006949:Hyperlipidemias / Q000097:blood* / Q000453:epidemiology / Q000276:immunology*; D007074:Immunoglobulin G / Q000737:chemistry; D008024:Ligands; D008071:Lipoprotein Lipase / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology*; D008954:Models, Biological; D014280:Triglycerides / Q000737:chemistry
chemical_list: D001323:Autoantibodies; D002914:Chylomicrons; D007074:Immunoglobulin G; D008024:Ligands; D014280:Triglycerides; D008071:Lipoprotein Lipase