title: A direct method for the calculation of alloreactive CD4+ T cell precursor frequency.
abstract: BACKGROUND
  Direct measurement of the precursor frequency of alloreactive CD4+ T cells has been impossible due to the lack of a specific means of determining the absolute number of daughter cells generated with each division in a repertoire of stimulated T cells.
  
  
  METHODS
  Responder lymphocytes were fluorescently labeled and adoptively transferred into irradiated allogeneic stimulator mice or incubated in vitro with irradiated stimulator splenocytes. After a 65- to 70-hr stimulation period, responder cells were analyzed by flow cytometry.
  
  
  RESULTS
  The precursor frequency of dividing CD4+ T cells was determined both in vivo and in vitro. The observed number of alloreactive daughter cells generated with each round of division was used to calculate the frequency of alloantigen-specific CD4+ T cells.
  
  
  CONCLUSIONS
  A novel method for the direct calculation of the frequency of alloreactive CD4+ T cells is described. This technique allows the determination of changes in the frequency of alloreactive T cells that might underlie tolerance to alloantigens.
authors.affiliation: Department of Surgery, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
authors.forename: H
authors.initials: H
authors.lastname: Noorchashm
authors.forename: Y K
authors.initials: YK
authors.lastname: Lieu
authors.forename: S Y
authors.initials: SY
authors.lastname: Rostami
authors.forename: H K
authors.initials: HK
authors.lastname: Song
authors.forename: S A
authors.initials: SA
authors.lastname: Greeley
authors.forename: S
authors.initials: S
authors.lastname: Bazel
authors.forename: C F
authors.initials: CF
authors.lastname: Barker
authors.forename: A
authors.initials: A
authors.lastname: Naji
mesh_terms: D000818:Animals; D018791:CD4 Lymphocyte Count / Q000379:methods*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D002455:Cell Division / Q000502:physiology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology*; D007519:Isoantigens / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D014181:Transplantation Immunology
chemical_list: D018984:Epitopes, T-Lymphocyte; D007519:Isoantigens