Binding, internalization and degradation of radio-iodinated interleukin 3 and granulocyte-macrophage colony stimulating factor by various hemopoietic cells.
The proliferation and differentiation of hemopoietic committed progenitor cells depend on colony stimulating factors (CSF). However, isolated mouse granulocyte-macrophage progenitor cells can still undergo limited proliferation in serum-free cultures after CSF deprivation. To test whether this is due to an accumulated pool of internalized factor, we examined the binding, internalization and degradation of radiolabelled interleukin 3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) in various hemopoietic cells. We found 20,000 high affinity IL-3 receptors on cells of two IL-3-dependent hemopoietic cell lines, FDC-P1 and FDC-P2 (Kd = 85 and 129 pM). FDC-P1 cells, which also respond to GM-CSF, possess 600 high-affinity GM-CSF receptors (Kd = 64 pM). Cells of both lines internalize IL-3, but only FDC-P1 cells release degraded IL-3 at a rapid rate. Both cell lines have similar dose-response curves for IL-3 and survival kinetics after factor removal. All other cells tested behave like FDC-P1, suggesting that the metabolism of IL-3 by FDC-P2 is exceptional. Our study indicates that transient proliferation of committed progenitor cells in the absence of added factors is apparently not due to a stable pool of internalized CSF but merely represents an intrinsic capability of these cells.
Péléraux
A
A
Swiss Institute for Experimental Cancer Research, Epalinges s/Lausanne.
Eliason
J F
JF
Odartchenko
N
N
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D007377:Interleukin-3 / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D051379:Mice; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D016185:Receptors, Interleukin-3 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature
D007377:Interleukin-3; D007457:Iodine Radioisotopes; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor