title: Increased levels of CD34+ hemopoietic progenitor cells in atopic subjects.
abstract: We investigated the contribution of hemopoietic progenitors to the accumulation of inflammatory cells in allergic airways disease. Using a multiparameter flow-cytometric method, the detection of peripheral blood (PB) and bone marrow (BM) cells expressing CD34, a progenitor cell marker, was explored. True CD34+ blast cells were detected as a discrete cluster exhibiting low intensity CD45 expression, low granularity, and low to intermediate cell size. A significantly greater number of CD34+ cells was detected in the PB of atopic individuals (1,438 +/- 347/10(6) nonadherent mononuclear cells [NAMNC], n = 19) compared with nonatopics (236 +/- 77/10(6) NAMNC, n = 13; P = 0.006). Similarly, in BM samples, a significantly greater number of CD34+ cells was detected in atopic (17,537 +/- 4,986/10(6) NAMNC, n = 7) compared with nonatopic subjects (6,422 +/- 1,853/10(6) NAMNC, n = 13, P = 0.02). Greater numbers of total colony-forming units (CFU) (granulocyte/macrophage [GM] and Eo/Baso) were present in cultures of PB NAMNC from atopics (24 +/- 5 CFU/10(6) NAMNC) cultured with recombinant human interleukin 5 (rhIL-5) (1 ng/ml) compared with nonatopics (5 +/- 2 CFU/10(6) NAMNC; P = 0.003). Analyses of colony subtypes showed significantly greater numbers of IL-5-responsive Eo/Baso-CFU in cultures from atopics (15 +/- 2 CFU/10(6) NAMNC) compared with nonatopics (5 +/- 2 CFU/10(6) NAMNC; P = 0.011). In contrast, no significant differences in colony counts were found between the two subject groups in cultures with rhIL-3 (1 ng/ml) or rhGM-CSF (10 ng/ml). A positive correlation was observed between PB CD34+ cell numbers and total CFU in cultures with rhIL-5 (r = 0.43, n = 32, P = 0.01) and rhGM-CSF (r = 0.45, n = 32, P = 0.009). Purging BM NAMNC with an anti-CD34 monoclonal antibody completely abrogated in vitro colony growth, supporting the view that a subset of CD34+ cells represents the relevant population of progenitors growing in culture. These data indicate that flow cytometric estimation of CD34+ cells is predictive of the colony-forming capacity of the sample and may be a useful alternative tool to clonogenic assays for enumerating progenitors. In addition, raised levels of CD34+ cells and IL-5-responsive Eo/Baso-CFU in atopics, including patients with atopic asthma, indicate a role for progenitors in allergic airways disease.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Sehmi
authors.forename: K
authors.initials: K
authors.lastname: Howie
authors.forename: D R
authors.initials: DR
authors.lastname: Sutherland
authors.forename: W
authors.initials: W
authors.lastname: Schragge
authors.forename: P M
authors.initials: PM
authors.lastname: O'Byrne
authors.forename: J A
authors.initials: JA
authors.lastname: Denburg
mesh_terms: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34 / Q000032:analysis / Q000097:blood*; D001854:Bone Marrow Cells; D002448:Cell Adhesion; D002454:Cell Differentiation; D002455:Cell Division; D002469:Cell Separation; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D005434:Flow Cytometry / Q000379:methods; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000737:chemistry; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000097:blood* / Q000473:pathology; D018189:Immunomagnetic Separation; D007377:Interleukin-3 / Q000494:pharmacology; D015848:Interleukin-5 / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000166:cytology; D011994:Recombinant Proteins; D012220:Rhinitis / Q000097:blood / Q000473:pathology; D013908:Thoracotomy
chemical_list: D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; D007377:Interleukin-3; D015848:Interleukin-5; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor