title: A point of care test for the determination of amniotic fluid interleukin-6 and the chemokine CXCL-10/IP-10.
abstract: OBJECTIVE
  Intra-amniotic inflammation is a mechanism of disease implicated in preterm labor, preterm prelabor rupture of membrane, cervical insufficiency, a short cervix, and idiopathic vaginal bleeding. Determination of interleukin (IL)-6 with immunoassays has been proven for more than two decades to be an excellent method for the detection of intra-amniotic inflammation. However, assessment of IL-6 for this indication has been based on immunoassays which are not clinically available, and this has been an obstacle for the implementation of this test in clinical practice. It is now possible to obtain results within 20 min with a point of care (POC) test which requires minimal laboratory support. This test is based on lateral flow-based immunoassay. The objective of this study was to compare amniotic fluid (AF) IL-6 and interferon-γ - inducible protein 10 (IP-10 or CXCL-10) concentrations determined using lateral flow-based immunoassay or POC test and standard enzyme-linked immunosorbent assay (ELISA) techniques.
  
  
  METHODS
  AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 20). AF IL-6 and IP-10 concentrations were determined by lateral flow-based immunoassay and ELISA. Intra-amniotic inflammation was defined as AF IL-6 ≥ 2.6 ng/ml. AF IL-6 and IP-10 concentrations between two assays were compared.
  
  
  RESULTS
  (1) Lateral flow-based immunoassay POC AF IL-6 and IP-10 test results were strongly correlated with concentrations of this cytokine/chemokine determined by ELISA (Spearman's ρ = 0.92 and 0.83, respectively, both p < 0.0001); (2) AF IL-6 concentrations determined by the lateral flow-based immunoassay test were, on average, 30% lower than those determined by ELISA, and the median difference was statistically significant (p < 0.0001); and (3) in contrast, AF IP-10 concentrations determined by the lateral flow-based immunoassay test were, on average, only 7% lower than those determined by ELISA, and the median difference was not statistically significant (p = 0.81).
  
  
  CONCLUSIONS
  AF IL-6 and IP-10 concentrations determined using a lateral flow-based immunoassay POC are strongly correlated with concentrations determined by conventional ELISA. This justifies further studies about the diagnostic indices and predictive values of this POC test.
authors.affiliation: a Perinatology Research Branch, Program for Perinatal Research and Obstetrics, Division of Intramural Research , Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH , Bethesda, MD and Detroit, MI , USA .
authors.forename: Piya
authors.initials: P
authors.lastname: Chaemsaithong
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Korzeniewski
authors.forename: Zhong
authors.initials: Z
authors.lastname: Dong
authors.forename: Lami
authors.initials: L
authors.lastname: Yeo
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Hassan
authors.forename: Yeon Mee
authors.initials: YM
authors.lastname: Kim
authors.forename: Bo Hyun
authors.initials: BH
authors.lastname: Yoon
authors.forename: Tinnakorn
authors.initials: T
authors.lastname: Chaiworapongsa
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry* / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000032:analysis* / Q000378:metabolism; D002821:Chorioamnionitis / Q000175:diagnosis* / Q000378:metabolism; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000175:diagnosis / Q000378:metabolism; D006801:Humans; D007118:Immunoassay / Q000379:methods; D015850:Interleukin-6 / Q000032:analysis* / Q000378:metabolism; D007752:Obstetric Labor, Premature / Q000175:diagnosis / Q000378:metabolism; D019095:Point-of-Care Systems; D011247:Pregnancy; D055815:Young Adult
chemical_list: C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; C508600:IL6 protein, human; D015850:Interleukin-6
keywords: Amniocentesis; MIAC; chronic chorioamnionitis; interferon-γ – inducible protein 10 (IP-10); intra-amniotic inflammation/infection; lateral flow-based immunoassay; prematurity; sterile inflammation