title: Novel automated pulse immunoassay for human alpha-fetoprotein.
abstract: BACKGROUND
  To improve current alpha-fetoprotein (AFP) assays, which are expensive and time-consuming, a specific AFP reagent has been developed for practical use in our newly developed high-speed, highly sensitive pulse immunoassay (PIA) system, in which a latex immunoagglutination reaction is carried out under a high-frequency pulse voltage, leading to an enhanced immunological reaction.
  
  
  METHODS
  We evaluated the assay performance (reproducibility, sensitivity, dilution linearity, interference) of the newly developed automated AFP PIA compared with the current AFP assay.
  
  
  RESULTS
  Using pooled serum samples, the within-run reproducibility resulted in a correlation variation of 3.6-4.7%. The AFP assay detection limit was determined to be 2.5 microg/L. Linear sequential dilution was found up to nearly 700 microg/L. Even up to an AFP concentration of 1.0 g/L, the prozone phenomenon was not observed. Free and conjugated bilirubin, haemolytic haemoglobin, chyle and rheumatoid factor did not show any test interference. Using AFP-positive serum samples from 114 patients, the correlation between our PIA and a chemiluminescence immunoassay resulted in an excellent correlation coefficient of 0.994.
  
  
  CONCLUSIONS
  The performance of AFP reagents in the PIA device shows that the system has excellent speed and equal sensitivity and specificity compared with the most highly sensitive conventional method. Our PIA system thus appears ready for use in the clinical diagnosis setting.
authors.affiliation: R&D Division, Pulse ImmunoTech Corporation, Katayanagi Institute, Tokyo University of Technology, Hachioji, Tokyo, Japan. iwata@pit-jp.com
authors.forename: Keisuke
authors.initials: K
authors.lastname: Iwata
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Kanayama
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Sahara
authors.forename: Isao
authors.initials: I
authors.lastname: Karube
authors.forename: Nobuo
authors.initials: N
authors.lastname: Inaba
authors.forename: Shinji
authors.initials: S
authors.lastname: Fujino
authors.forename: Mikihiko
authors.initials: M
authors.lastname: Kawano
authors.forename: Ikunosuke
authors.initials: I
authors.lastname: Sakurabayashi
mesh_terms: D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007841:Latex Fixation Tests / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D035501:Uncertainty; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: C097353:AFP protein, human; D000509:alpha-Fetoproteins