HLA-DR inhibits granulocytic differentiation without inducing apoptosis of CD34 cells.
Hematopoietic progenitors express HLA-DR molecules. However the significance of HLA-class II molecules on CD34+ cells remains unknown. The primary role of HLA-class-II molecules is antigen presentation although a second role, that of signal transduction, has been established in B cells. The role of HLA-DR in hematopoiesis was examined by determining the ability of CD34+ progenitor cells to differentiate to "Colony Forming Unit Granulocyte-Macrophage" (CFU-GM) and "Burst Forming Unit Erythrocyte" (BFU-E) in the presence of anti-HLA-DR monoclonal antibody. We observed a reduction in the number of CFU-GM which was due in part to down regulation of granulocyte rather than monocyte differentiation. These observations suggest that HLA-DR signals can regulate myelopoiesis. We point out especially the role of the HLA-DR molecule in the switch of CFU-GM between granulocyte or monocyte lineages. Although HLA-DR mediated apoptosis has been described in mature B lymphocytes apoptosis of CD34+ cells was excluded as a mechanism.
Bertho
N
N
Laboratoire Universitaire d'Hématologie et de Biologie des Cellules Sanguines, INSERM CRI 4U006B-UPRES EA 22-33, Rennes, France.
Drénou
B
B
Mooney
N
N
Amiot
L
L
Langanay
T
T
Le Berre
C
C
Charron
D
D
Fauchet
R
R
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D018952:Antigens, CD34 / Q000302:isolation & purification*; D017209:Apoptosis; D002454:Cell Differentiation; D003114:Colony-Forming Units Assay; D053222:Fas Ligand Protein; D006098:Granulocytes / Q000166:cytology*; D006684:HLA-DR Antigens / Q000378:metabolism*; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D006801:Humans; D016256:Lewis X Antigen / Q000302:isolation & purification; D018950:Lipopolysaccharide Receptors / Q000302:isolation & purification; D008264:Macrophages / Q000166:cytology; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism; D009000:Monocytes / Q000166:cytology; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; D018952:Antigens, CD34; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D006684:HLA-DR Antigens; D016256:Lewis X Antigen; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D019014:fas Receptor