Production of granulocyte-macrophage colony-stimulating factor by primary
cultures of unstimulated rat microvascular endothelial cells
DG Malone, JH Pierce, JP Falko and DD Metcalfe
Mast Cell Physiology Section, National Institute of Allergy and Infectious
Diseases, Bethesda, MD.
Small vessel (microvascular) endothelial cells are in close contact with
hematopoietic progenitor cells in the bone marrow and therefore may have an
important role in hematopoiesis. Although other studies have shown that
endothelial cells produce various colony-stimulating factors (CSFs), these
studies examined large vessel endothelial cells, which are different in
many respects from microvascular endothelial cells and which do not contact
cells in the bone marrow. We show in this study that primary cultures of
unstimulated rat fat capillary endothelial cells grown in serum-free medium
produce a substantial amount of granulocyte-macrophage CSF (GM-CSF). The
medium conditioned by these cells stimulated proliferation of two different
lines of GM- CSF-responsive cells--PT-18 mast cells and FDC-P1 cells--and
supported the growth of cells of the granulocyte and macrophage lines in
cultures of rat bone marrow cells. The factor responsible for this activity
had physical properties consistent with those of GM-CSF, namely, a similar
apparent mol wt by gel filtration, resistance to repeated freeze-thaws,
resistance to boiling for ten minutes but not for 30 minutes, and
resistance to heating to 56 degrees C for one hour. The factor causing
target cell stimulation was not B cell-stimulating factor-1 (BSF-1, or IL
4), since it failed to stimulate a BSF-1-responsive cell line HT2- JH, and
target cells (PT-18) did not respond appreciably to recombinant BSF-1.
Northern blot analysis of mRNA from rat fat capillary endothelial cells
showed high levels of expression of GM-CSF, confirming that this factor is
produced by microvascular endothelial cells. This is the first report of
CSF production by unstimulated microvascular endothelial cells,
demonstrating that these ubiquitous cells are capable of producing sizable
amounts of at least one growth factor for hematopoietic progenitor cells.
Volume 71,
Issue 3,
pp. 684-689,
03/01/1988
Copyright © 1988 by The American Society of Hematology
