| Abstract |
Committed precursor cells for granulocyte and macrophage differentiation
can proliferate in soft agar cultures to form colonies of ganulocytes
and/or macrophages. Colonies arise from individual colony forming cells.
Colony formation is wholly dependent upon the constant presence of colony-
stimulating factor (CSF), a stimulotary glycoprotein substance. Recent
studies suggest that there are subclasses of CSF, differing in their
biochemical properties and target cell specificities. CSF is usually
quantitated by an in vitro assay based on the proliferative effects of
this factor on its target cell in bone marrow, by way of the CSF dependent
formation of granulocyte and/or macrophage colonies by bone marrow cells
in soft agar cultures. Quantitation is based on the relationship that
exists between colony number and CSF concentration using a constant number
of bone marrow cells (usually 10^5 cells/plate). Such an assay takes at
least 7 days and requires: a) differentiation between colonies (>50 cells)
and a cluster of cells (<50 cells); b) identification of the type of
colony (granulocyte, macrophage or mixture of both); and c) counting the
number of colonies. It would therefore be advantageous if CSF could be
quantitated by a rapid and more objective assay, which can identify the
subclass of CSF as well.
In the present study, we report on a cell line, PT-18, that is dependent
on mouse lung conditioned medium (GM-CSF) for its proliferation. Thus this
cell line can be utilized to rapidly assay CSF and, in addition, to
identify this particular subclass of CSF.
|
|---|
