Circulating CD34+ cells in cord blood and mobilized blood have a different profile of adhesion molecules than bone marrow CD34+ cells.
The expression of adhesion molecules was studied on CD34+ hematopoietic precursors in cord blood, bone marrow and mobilized blood. The samples were labeled in a double immunofluorescence procedure with a CD34 monoclonal antibody and with antibodies against maturation and differentiation antigens and adhesion molecules. Myeloid precursors formed the majority of the CD34+ cells in all samples. In bone marrow a separate cluster of B-cell precursors with low forward scatter was present. Nearly all CD34+ cells in normal bone marrow expressed VLA-4 and VLA-5, PECAM-1, LFA-3 and HCAM. The majority of the CD34+ cells also had LFA -1 and L-selectin on the surface membrane. A small subset was VLA-2, VLA-3, ICAM-1 or Mac-1 positive. CD34+ cells expressing the vitronectin receptor or the CD11c antigen were rare. Cord blood and mobilized blood CD34+ cells had a lower expression of VLA-2, VLA-3 and VLA-5 and a higher expression of LFA-1, ICAM-1 and L-selectin than bone marrow CD34+ cells. Except for LFA-1, this was not due to the presence of more myeloid precursors in these samples. Low beta1 integrin expression may lead to less adhesion to the extracellular matrix. High expression of L-selectin may facilitate interaction with endothelial cells. Therefore, this phenotype may favour mobilization.
Asosingh
K
K
Department of Laboratory Hematology, Academic Hospital, Free University Brussels (VUB), Belgium.
Renmans
W
W
Van der Gucht
K
K
Foulon
W
W
Schots
R
R
Van Riet
I
I
De Waele
M
M
D000328:Adult; D015703:Antigens, CD / Q000378:metabolism*; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000276:immunology; D001853:Bone Marrow / Q000276:immunology*; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007223:Infant; D016023:Integrins / Q000378:metabolism*; D010641:Phenotype; D019087:Selectins / Q000378:metabolism*
D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D016023:Integrins; D019087:Selectins