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JM Heard, S Fichelson and B Varet
The involvement of colony-stimulating activity (CSA) in murine long- term
bone marrow cultures (LTBMC) was studied using bilayer agar cultures. The
supernatants of LTBMC were removed, a layer of dense agar was spread over
the cells adherent to the bottom of the flask, and fresh myeloid cells were
plated as source of CFU-C in an upper agar layer. Large numbers of
granulocytic and macrophagic colonies developed regularly when target cells
were plated over adherent cells of nonrecharged and greater than 12 wk old
LTBMC that were hematopoietically inactive (i.e., producing a low number of
nonadherent cells). The removal of adherent cells from the myeloid cells
used as source of CFU-C did not decrease the number of colonies. This
suggests that adherent cells of LTBMC release CSA that is directly active
on CFU- C. This CSA was no longer detectable over adherent layers of
hematopoietically active LTBMC. A close inverse relationship was
demonstrated between the number of nonadherent cells harvested before the
assay and the level of CSA. No inhibitor for CSA was demonstrated in the
supernatant of hematopoietically active cultures. Murine exogenous CSA
incubated over the adherent layer host its activity within 24 hr, whereas
in the same conditions human CSA retained its activity. These data
demonstrate the production of CSA by the adherent layer of LTBMC and
strongly suggest its specific in situ consumption by differentiating
myeloid cells.
This article has been cited by other articles:
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| Copyright © 1982 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
