The human burst-forming unit-megakaryocyte (BFU-MK) is a primitive megakaryocytic progenitor cell. A marrow cell population enriched for BFU-MK (CD34+ DR-) was obtained by monoclonal antibody labeling and fluorescence-activated cell sorting. CD34+DR- cells were assayed in a serum-depleted, fibrin clot culture system. Recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF), recomb...

Peripheral blood hematopoietic progenitors (PBHP) are capable of colony growth in vitro. The effect of stem cell factor (SCF), interleukin-6 (IL-6), and basic fibroblast growth factor (bFGF) on myeloid colony proliferation of PBHP was determined. PBHP purified by positive selection with CD34-specific antibody were plated in semisolid agarose with reported plateau doses of interleukin-3 (IL-3), ...

Purified natural (n) and recombinant (r) murine (mu) mast cell growth factor (MGF, a c-kit ligand) were evaluated alone and in combination with r human (hu) erythropoietin (Epo), rhu granulocyte-macrophage colony-stimulating factor (rhuGM-CSF), rhuG-CSF, and/or rhuM-CSF for effects in vitro on colony formation by multipotential (colony-forming unit-granulocyte, erythroid, monocyte, megakaryocyt...

Effects of interleukin-6 (IL-6) on cycling status and clonogenic maturation of human fetal (cord blood) and adult hematopoietic progenitors were compared. Adult marrow cells were incubated for various lengths of time with various concentrations of IL-6, in a serum-free system, after which tritiated thymidine suicide studies were performed. After incubation of 2 to 5 x 10(6) cells/mL for 4 hours...

Transforming growth factor beta (TGF-beta), a polypeptide present in abundant amounts in bone matrix, was examined for its effects on osteoclast formation by using a human bone marrow culture system in which multinucleated cells (MNCs) with osteoclast characteristics form. TGF-beta strongly inhibited MNC formation at concentrations as low as 1 ng/ml. TGF-beta also completely suppressed the effe...

The effects of mouse L-cell interferon (IFN) on growth of mouse bone marrow cells and their differentiation into macrophages and granulocytes were investigated in a liquid suspension culture system with two different types of colony-stimulating factor (CSF). Within 7 days, most bone marrow cells differentiated into macrophages in the presence of macrophage colony-stimulating factor (M-CSF) deri...

Hematopoietic regulatory factors produced by adherent (stromal) cells in long-term murine bone marrow cultures have been investigated. Using an in situ double layer agar overlay system, we demonstrated that exposure of the stromal cells to 1,100-rad irradiation increased their activities in stimulating colony formation of FDC-P1, an interleukin 3 (IL 3)-responsive cell line. The colony-stimulat...

We investigated the interactions between human erythropoietin (hEpo) and serum factor(s) on murine megakaryocyte (MK) colony formation. Serum-free cultures supported the growth of a large number of murine MK colonies in the presence of murine interleukin-3 (mIL-3). The addition of fetal calf serum (FCS) to mIL-3-containing cultures resulted in only a minimal increase in the number of murine MK ...

Previous studies using unseparated normal human bone marrow cells have indicated that recombinant tumor necrosis factor a (rTNF-a) can inhibit the //; vitro colony growth by normal granulocyte/macrophage (CFU-GM) and erythroid (BFU-E) progenitor cells in a dose-dependent manner. In the present studies, by using very low numbers of highly enriched normal bone marrow progenitor cell populations a...

Human recombinant interleukin-4 (IL-4) was studied for its effects on myeloid progenitor cells from normal and leukemic bone marrow cells in the presence and absence of additional growth factors. IL-4 itself did not support myeloid cluster or colony formation (CFU-GM). However, cultures supplied with IL-4 (300 U/mL) and IL-3 demonstrated a significant decline in myeloid colony numbers (CFU-GM) ...