A soluble activity from adherent marrow cells cooperates with IL 3 in
stimulating growth of pluripotential hematopoietic precursors
NN Iscove, B Fagg and G Keller
Ontario Cancer Institute, Toronto, Canada.
Marrow cells from 5-fluorouracil (5-FU)-treated mice formed few or no mixed
erythroid colonies when plated in semisolid medium with interleukin 3 (IL
3) and erythropoietin (Ep) alone. When conditioned medium (CM) from
plastic-adherent marrow or thymus cells was also included, however, growth
of mixed erythroid colonies was strongly stimulated. Both IL 3 and the
accessory activity (AA) had to be present at the initiation of the cultures
for growth to occur. AA was also produced by a cloned immortalized line
(95/1.7) of fibroblastoid marrow cells that lacked macrophage-specific cell
surface markers. Colony- stimulating factor-1 (CSF-1) was also released,
but not granulocyte colony-stimulating activity. When 95/1.7 CM was
analyzed by gel filtration, AA eluted with an apparent size of 35 kd and
separated completely from the CSF-1. Biologic assays failed to detect IL 1
or IL 3 activity in 95/1.7 CM. Growth of mixed erythroid colonies from
5-FU- treated marrow is thus stimulated by adherent marrow cell-derived
factors that appear distinct not only from the known CSFs including IL 3,
but also from IL 1.
Volume 71,
Issue 4,
pp. 953-957,
04/01/1988
Copyright © 1988 by The American Society of Hematology
