title: An interleukin-23 binding protein in mid-trimester amniotic fluid.
abstract: OBJECTIVE
  The binding of mid-trimester amniotic fluid to cytokines was evaluated.
  
  
  METHODS
  Purified tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-10, IL-12, and IL-23 were incubated with amniotic fluid from 25 women undergoing a mid-trimester amniocentesis, or with bovine serum albumin or saline, and cytokine binding to monoclonal antibodies was quantitated by ELISA. Aliquots of amniotic fluid were heated to 95 degrees C for 15 min and then retested for IL-23 binding. The effect of amniotic fluid dilution on IL-23 quantitation was evaluated.
  
  
  RESULTS
  All amniotic fluids had a negligible effect on TNF-alpha, IL-10, and IL-12 detection. In marked contrast, pre-incubation with amniotic fluid from each subject reduced the subsequent ability to detect IL-23 by >50%. The extent of inhibition was directly proportional to the amniotic fluid dilution and was markedly reduced following heating at 95 degrees C for 15 min. Amniotic fluids from White, Black, Asian, East Indian, and Hispanic women were equally effective.
  
  
  CONCLUSIONS
  Interleukin-23 and IL-12 share a common p40 subunit and no inhibition of IL-12 was apparent. It appeared that a component of mid-trimester amniotic fluid specifically interacts with the p19 subunit unique to IL-23. Mid-trimester amniotic fluid reactivity with IL-23 may be a mechanism to limit intra-amniotic neutrophil-derived inflammation.
authors.affiliation: Department of Obstetrics and Gynecology, New York Hospital Queens Medical Center, New York, NY, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Herway
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Bongiovanni
authors.forename: Daniel
authors.initials: D
authors.lastname: Skupski
authors.forename: Steven S
authors.initials: SS
authors.lastname: Witkin
mesh_terms: D000653:Amniotic Fluid / Q000276:immunology / Q000378:metabolism*; D000911:Antibodies, Monoclonal; D001667:Binding, Competitive; D005260:Female; D006358:Hot Temperature; D006801:Humans; D007108:Immune Tolerance; D016753:Interleukin-10 / Q000378:metabolism; D018664:Interleukin-12 / Q000378:metabolism; D053759:Interleukin-23 / Q000276:immunology / Q000378:metabolism*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011485:Protein Binding; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D053759:Interleukin-23; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D018664:Interleukin-12