title: Imbalanced "memory" T lymphocyte subsets and analysis of dendritic cell precursors in the peripheral blood of adult patients with Langerhans cell histiocytosis.
abstract: OBJECTIVE
  To investigate the phenotype of lymphocytes and dendritic cell precursors in the peripheral blood of adult patients with histiocytosis X.
  
  
  METHODS
  Data were obtained on patients with histiocytosis X treated in La Pitié-Salpetrière Hospital. Peripheral blood mononuclear cells from 10 patients (4 with unifocal and 6 with disseminated disease) were studied by flow cytometry. A method was set up to detect circulating Langerhans cells, dendritic cells and their precursors.
  
  
  RESULTS
  An abnormal repartition of "memory" T lymphocyte subsets was observed, with a significant decrease of CD4CD45RO and CD8CD45RO and a reciprocal increase of CD4CD45RA "naive" cells, while CD4+ cells displaying the accessory molecule CD28 were decreased in some patients. These abnormalities disappeared in vitro after triggering of the CD3 and CD28 molecules in the absence of antigen presenting cells, hence demonstrating that there was no constitutive defect in the capacity of CD4+ and CD8+ T cells to convert from the CD45RO- to the CD45RO+ isoform. Langerhans cells were undetectable in the peripheral blood, and dendritic cells and their precursors were present in normal proportions (0.5 +/- 0.2% and 2.8 +/- 1.2%, respectively), but the latter were more numerous (4% and 6% of the PBMC) in the two patients with the more severe form of the disease.
  
  
  CONCLUSIONS
  We found in these patients some T lymphocyte phenotype abnormalities which suggest alterations in antigen-driven activation processes. The number of dendritic precursor cells was not consistently elevated in the peripheral blood from histiocytosis X patients.
authors.affiliation: Laboratoire d'Immunologie Cellulaire (URA CNRS 625), La Pitié-Salpetrière Hospital, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Hosmalin
authors.forename: D
authors.initials: D
authors.lastname: McIlroy
authors.forename: B
authors.initials: B
authors.lastname: Autran
authors.forename: J P
authors.initials: JP
authors.lastname: Ragot
authors.forename: P
authors.initials: P
authors.lastname: Debré
authors.forename: S
authors.initials: S
authors.lastname: Herson
authors.forename: M
authors.initials: M
authors.lastname: Karmochkine
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D003713:Dendritic Cells / Q000737:chemistry / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D006684:HLA-DR Antigens / Q000032:analysis; D006412:Hematopoietic Stem Cells / Q000737:chemistry / Q000276:immunology*; D006646:Histiocytosis, Langerhans-Cell / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory / Q000276:immunology*; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D015375:Receptors, Interleukin-2 / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000166:cytology / Q000276:immunology*
chemical_list: D015415:Biomarkers; D006684:HLA-DR Antigens; D015375:Receptors, Interleukin-2; D017493:Leukocyte Common Antigens