title: Quantification of adult T-cell leukemia/lymphoma cells using simple four-color flow cytometry.
abstract: BACKGROUND
  The absolute number of adult T-cell leukemia/lymphoma (ATL) cells in peripheral blood is an essential indicator to evaluate disease status. However, microscopically counting ATL cells based on morphology requires experience and tends to be inaccurate due to the rarity of ATL.
  
  
  METHODS
  Based on our research showing that acute-type ATL cells are specifically enriched in the CD4+/CD7- (CD7N) fraction, a new analytical method to accurately quantify ATL cells was established using an internal bead standard and simple four-color flow cytometry. This method was verified by comparison with microscopic examination of 49 peripheral blood samples and used to follow up patients.
  
  
  RESULTS
  A strong correlation was observed between the number of CD7N cells measured by flow cytometry and the number of abnormal lymphocytes measured microscopically by experienced technicians [Pearson's R, 0.963; Spearman's rho, 0.921; intercorrelation coefficient, 0.962]. The linear regression coefficient was close to 1 (β=1.013). Our method could detect 1 cell/μL, and the limit of quantitation was between 2.9 and 9.8 cells/μL. The frequency of CD7N cells among CD4+ cells changed during chemotherapy, which reflected differences between chemosensitive and chemoresistant cases. Kaplan-Meier analysis with a log-rank test showed that patients with decreased CD7N proportion after chemotherapy had significantly longer disease-specific survival (p=0.003).
  
  
  CONCLUSIONS
  Our newly established method quantified tumor cells in patients with acute-type ATL. Furthermore, this method was useful for assessing the efficacy of chemotherapy, and the change of the CD7N proportion could be more important to predict prognosis.
authors: Tomohiro
authors: T
authors: Ishigaki
authors: Yuji
authors: Y
authors: Zaike
authors: Masanori
authors: M
authors: Nojima
authors: Seiichiro
authors: S
authors: Kobayashi
authors: Nobuhiro
authors: N
authors: Ohno
authors: Kaoru
authors: K
authors: Uchimaru
authors: Arinobu
authors: A
authors: Tojo
authors: Hiromitsu
authors: H
authors: Nakauchi
authors: Nobukazu
authors: N
authors: Watanabe
mesh_terms: D000328:Adult; D000368:Aged; D015704:CD4 Antigens / Q000378:metabolism; D002452:Cell Count; D003116:Color; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D015704:CD4 Antigens