IL-5 expression and release from human CD34 cells in vitro; ex vivo evidence from cases of asthma and Churg-Strauss syndrome.
BACKGROUND
Eosinophils develop from hematopoietic CD34(+) progenitor cells in the bone marrow (BM) under the influence of Interleukin-5 (IL-5). The primary source of IL-5 is T-lymphocytes, although other sources may exist. The aims of this study were to determine whether CD34(+) cells from human peripheral blood (PB) and BM have the capacity to produce IL-5 when stimulated in vitro, and secondly, whether an elevated number of IL-5-producing CD34(+) cells can be found in situ in ongoing eosinophilic disease.


METHODS
CD34(+) cells from PB and BM were stimulated in vitro, and IL-5 production and release was assessed by ELISA, ELISPOT, flow cytometry and immunocytochemistry. Blood and BM from a patient with Churg-Strauss syndrome were analyzed by flow cytometry for CD34(+)/IL-5(+) cells, and immunohistochemical staining of CD34(+)/IL-5(+) cells in bronchial biopsies from an asthmatic patient was performed.


RESULTS
Both PB and BM CD34(+) cells can produce and release IL-5 when stimulated in vitro. In the Churg-Strauss patient, IL-5-producing CD34(+) cells were found in PB and BM. Oral glucocorticoid treatment markedly decreased the number of IL-5-positive CD34 cells in the BM. CD34(+)/IL-5(+) cells were present in a patient with asthma.


CONCLUSIONS
CD34(+) cells in blood and BM are capable of producing IL-5 both in vitro and in vivo in humans, arguing that these cells may have the capacity to contribute to eosinophilic inflammation. Consequently, targeting CD34(+) progenitor cells that produce and release IL-5 may be effective in reducing the mobilization of eosinophil lineage-committed cells in eosinophilic-driven diseases.
Bossios
A
A
Krefting Research Centre, Department of Internal Medicine, Institute of Medicine, Göteborg University, Sweden.
Sjöstrand
M
M
Dahlborn
A-K
AK
Samitas
K
K
Malmhäll
C
C
Gaga
M
M
Lötvall
J
J
D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism*; D001249:Asthma / Q000276:immunology / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D002469:Cell Separation; D015267:Churg-Strauss Syndrome / Q000276:immunology / Q000378:metabolism*; D004802:Eosinophilia / Q000209:etiology / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D015848:Interleukin-5 / Q000276:immunology / Q000378:metabolism*; D008875:Middle Aged
D018952:Antigens, CD34; D015848:Interleukin-5