The effects of interleukin 6 and interleukin 3 on early hematopoietic events in long-term cultures of human marrow.
Interleukin (IL)-6 and IL-3, both alone and in combination, stimulate hematopoietic cells in short-term in vitro assays and in vivo. To study their ability to influence hematopoiesis in a system that mimics many features of the marrow microenvironment, long-term cultures (LTC) were produced by co-cultivating normal human marrow cells on feeder layers of murine marrow-derived stromal cells (M2-10B4 cells) genetically engineered to produce human IL-6 and/or IL-3. Feeders stably producing 20 ng/ml IL-6 slightly increased the output of clonogenic progenitors in these LTC but did not change the production of mature (total nonadherent) cells as compared to control cultures. Feeders producing 50 ng/ml IL-3 increased both clonogenic progenitor output (approximately threefold) and the output of mature cells (six-fold) as compared to controls. Feeders producing both factors also increased the output of both progenitors and mature cells. At the time of the weekly half-medium change when primitive clonogenic progenitors in the adherent layer are quiescent, such progenitors were actively cycling in all cultures with factor-producing feeders, as shown by [3H]thymidine suicide assays. Similarly, three sequential daily additions of 20 ng/ml of IL-6 also stimulated the quiescent progenitors to enter S-phase 2 days later, although single doses of recombinant IL-6 as high as 100 ng/ml failed to do so. The combined presence of IL-6- and IL-3-producing feeders, but neither alone, was also able to enhance more than twofold the maintenance and early differentiation of cells capable of generating clonogenic cells for at least a further 5 weeks in secondary LTC. Thus, the provision of a continuous source of IL-6 or IL-3 to primitive hematopoietic cells even in the LTC system can enhance late events in the hierarchy of hematopoietic cell differentiation, but a combination of the two factors is required to stimulate early multipotent progenitors.
Otsuka
T
T
Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, Canada.
Thacker
J D
JD
Hogge
D E
DE
D000818:Animals; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D002999:Clone Cells; D015672:Erythroid Precursor Cells / Q000166:cytology; D006098:Granulocytes / Q000166:cytology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007377:Interleukin-3 / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D014162:Transfection
D007377:Interleukin-3; D015850:Interleukin-6; D011994:Recombinant Proteins