Development of multipotential haemopoietic stem cells to neutrophils is associated with increased expression of receptors for granulocyte macrophage colony-stimulating factor: altered biological responses to GM-CSF during development.
Interleukin-3 (IL-3) dependent multipotent haemopoietic stem cells FDCP-Mix A4 (A4) were induced to differentiate and develop into mature neutrophils in response to Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) plus granulocyte CSF (G-CSF). This resulted in an increase in cell number over seven days of culture, following which the cells lost the ability to undergo further proliferation. The effect of GM-CSF on these cells has been assessed at various stages of development. Clonogenic cells, able to respond to GM-CSF, were generated only at days 3, 4 post-induction. From day 5 onwards, mature post-mitotic neutrophils are produced and clonogenic cells are lost. Loss of proliferative potential, in response to GM-CSF, was confirmed using [3H]-thymidine incorporation. Receptors for GM-CSF, were also measured during development using [125I]-GM-CSF binding assays. Although the dissociation constant for GM-CSF binding sites did not vary considerably, the number of such sites increased dramatically from about 20 (day 0, when the cells have a primitive morphology) to about 1000 by day 6 (when the cells are predominantly mature neutrophils). GM-CSF-stimulated Na+/H+ antiport activation was also determined. Although few GM-CSF receptors are expressed at day 0, there is a significant response (63% of maximal) to GM-CSF in terms of intracellular alkalinisation: this response increased markedly until, by day 4 (700 GM-CSF binding sites/cell), there is a maximal activation of the antiport by GM-CSF. By day 7 (greater than 900 GM-CSF binding sites/cell), however, there is significant reduction in activation of the Na+/H+ antiport by GM-CSF. Nonetheless, increased viability of these mature cells is still seen in response to GM-CSF. These results suggest that not only does expression of GM-CSF receptors alter during development of multipotential cells to mature neutrophils, but that these receptors are coupled to different intracellular effector mechanisms as the cells progressively mature.
Heyworth
C M
CM
Cancer Research Campaign Department of Experimental Haematology, Paterson Institute for Cancer Research, Withington, Manchester, UK.
Hampson
J
J
Dexter
T M
TM
Walker
F
F
Burgess
A W
AW
Kan
O
O
Cook
N
N
Vallance
S J
SJ
Whetton
A D
AD
D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D003114:Colony-Forming Units Assay; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006410:Hematopoiesis / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000187:drug effects* / Q000378:metabolism
D007377:Interleukin-3; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor