title: [Study of anti-SSA 52-kDa and anti-SSA 60-kDa avidity antibodies in pregnant women].
abstract: BACKGROUND
  Neonatal lupus erythematosus (NLE) is a rare disorder caused by the transplacental passage of maternal autoantibodies and manifests with characteristic skin eruption and/or congenital heart block. Anti-SSA 52-kDa and 60-kDa antibodies are important serology markers of the diagnosis of NLE. However, women who have these antibodies do not always give birth to children with NLE. Therefore, we investigated the avidity (quality of the antibody) using urea.
  
  
  METHODS
  The sera of 97 women and 3 umbilical cord blood specimens were measured using commercial ELISA kit (MESACUP 52K SS-A/Ro and 60K SS-A/Ro, MBL). Avidity index was obtained using 8M urea.
  
  
  RESULTS
  The 21 mothers with infants demonstrating atrioventricular block (AB) showed higher antibody indexes for 52-kDa (p< 0.001) and 60-kDa (p=0.009) proteins than the 76 mothers of infants without AB. The 19 mothers with infants demonstrating AB had both anti-52-kDa and anti-60-kDa antibodies, and the 2 mothers had only anti-52-kDa antibody. They had higher avidity indexes to 60-kDa (p=0.026) than those without AB. A mother with infant demonstrating AB showed anti-52-kDa antibody isolated positive (96.0 Index), and showed low anti-52-kDa avidity antibody (6.3%). The case was a similar result in umbilical cord blood (75.8 Index, 6.0%).
  
  
  CONCLUSIONS
  We conjecture that anti-52-kDa and anti-60-kDa avidity antibodies influence the development of AB. Two mothers with infant demonstrating AB showed anti-52-kDa antibody isolated positive. A fetus could develop AB in maternal low anti-52-kDa avidity antibody.
authors.affiliation: Department of Laboratory Medicine, Osaka Prefectural Hospital Organization Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi 594-1101, Japan. miyano@mch.pref.osaka.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Miyano
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakayama
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood*; D000915:Antibody Affinity; D015415:Biomarkers / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D007518:Isoantibodies / Q000097:blood*; D008180:Lupus Erythematosus, Systemic / Q000151:congenital / Q000175:diagnosis; D008431:Maternal-Fetal Exchange; D008970:Molecular Weight; D011247:Pregnancy; D014508:Urea
chemical_list: D000974:Antibodies, Antinuclear; D015415:Biomarkers; D007518:Isoantibodies; C035356:SS-A antibodies; D014508:Urea