title: Four-color flow cytometry bypasses limitations of IG/TCR polymerase chain reaction for minimal residual disease detection in certain subsets of children with acute lymphoblastic leukemia.
abstract: OBJECTIVE
  Competitive immunoglobulin/T-cell receptor polymerase-chain reaction (PCR) analysis with fluorescent detection is a rapid, cheap and reproducible method for quantifying minimal residual disease (MRD), which is well adapted to the recognition of high-risk childhood acute lymphoblastic leukemia (ALL). We aimed at defining whether flow cytometry (FC) techniques can bypass limitations of PCR for MRD determination.
  
  
  METHODS
  We analyzed 140 remission samples from 91 patients using both competitive PCR amplification of antigen-receptor genes and four-color FC identification of leukemia immunophenotype. These methods were chosen with the aim of detecting at least 0.1% blasts.
  
  
  RESULTS
  MRD was measured using both PCR and FC methods in 123 samples and the two methods provided concordant results in 119 of them (97%). Moreover, three out of the four discordant results appeared minor since MRD was detectable by both methods, but at different levels. In 12 of 13 samples from nine patients, mainly infants with early CD10- and/or t(4;11) B-cell ALL and children with immature T-cell ALL, MRD could be determined using FC whereas PCR failed. Conversely, FC methods were unfeasible due to inappropriate leukemia immunophenotype in three additional children (including two with T-cell ALL) for whom PCR successfully provided MRD results.
  
  
  CONCLUSIONS
  The MRD results provided by FC techniques were highly concordant with those of competitive PCR. Moreover, the applicability of FC appeared higher in certain ALL subsets, although the appropriateness of this technique in terms of outcome prediction remains to be demonstrated.
authors.affiliation: Laboratoire d'Hématologie, Centre Hospitalier Universitaire, Nantes, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Robillard
authors.forename: Hélène
authors.initials: H
authors.lastname: Cavé
authors.forename: Françoise
authors.initials: F
authors.lastname: Méchinaud
authors.forename: Christine
authors.initials: C
authors.lastname: Guidal
authors.forename: Francine
authors.initials: F
authors.lastname: Garnache-Ottou
authors.forename: Pierre Simon
authors.initials: PS
authors.lastname: Rohrlich
authors.forename: Hervé
authors.initials: H
authors.lastname: Avet-Loiseau
authors.forename: Richard
authors.initials: R
authors.lastname: Garand
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007223:Infant; D018365:Neoplasm, Residual / Q000145:classification / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000145:classification / Q000235:genetics*