In order to determine whether human granulocyte-macrophage colony-stimulating factor (GM-CSF) can enhance phagocytosis. neutrophils were combined with Staphylococcus aureus (S aureus). and both the number of bacteria per neutrophil and the percent of neutrophils phagocytizing were assessed in the absence and presence of GM-CSF. Exposure to GM-CSF did not enable neutrophils to ingest unopsonized...

It is well established that protein malnutrition (PM) impairs immune defenses and increases susceptibility to infection. Macrophages are cells that play a central role in innate immunity, constituting one of the first barriers against infections. Macrophages produce several soluble factors, including cytokines and growth factors, important to the immune response. Among those growth factors, gra...

A cell line (designated BMpXT1) was generated from sheep bone marrow using the Moloney murine leukemia virus-based retroviral vector pXT1. BMpXT1 cells resembled mature alveolar macrophages in being adherent and esterase positive, in expressing certain cell surface antigens, and in secreting granulocyte-macrophage colony-stimulating factor (GM-CSF) when stimulated by ovine interferon-gamma and ...

The growth-promoting activities of interleukin-6 (IL-6) in combination with different factors were assessed in bone marrow (BM) cultures prepared from normal mice and from mice treated with 5-fluorouracil (5-FU). Effects on hematopoietic colony formation with respect to number, size, and cellular composition were evaluated. In agreement with previous reports, IL-6 acts synergistically with IL-3...

We have identified a molecule expressed by human marrow granulocyte/monocyte colony-forming cells (CFU-GM), erythroid colony-forming cells (CFU-E), and erythroid burst-forming units (BFU-E), but not their precursors detectable in long-term bone marrow culture. This antigen, detected by flow microfluorimetry using monoclonal antibody 7B9, is coexpressed with CD33 on many CD34+ CFCs, although onl...

Purified human transferrin. when saturated with iron or zinc, decreased the production of granulocyte-macrophage colony-stimulating factors (GM-CSF) by human T lymphocytes that had been stimulated by phytohemagglutin or concanavalin-A. The iron-saturated transferrin was more active than the zinc-saturated transferrin. This effect was not seen for copper-saturated transferrin or for apotransferr...

The effects of recombinant interleukin-6 (IL-6) on the proliferation of blast precursors present in the peripheral blood of patients with acute myeloblastic leukemia (AML) was investigated. IL-6 had little effect by itself; however, it synergized with granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) in the stimulation of AML blast colony formation. Responsivene...

Cell lines have been produced from long-term cultures of mouse bone marrow that require a factor, present in WEHI-3 conditioned medium (CM) or in spleen CM, for their sustained growth. The cell lines were obtained from nonvirus-treated cultures, are nonleukemic, maintain a normal karyotype, and form colonies showing granulocyte maturation when plated in soft agar. Granulocyte/macrophage (GM) co...

We previously reported the aberrant growth of granulocyte-macrophage (GM) progenitors induced by a combination of stem cell factor (SCF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in juvenile chronic myelogenous leukemia (JCML). We examined here the effects of thrombopoietin (TPO) on the proliferation and differentiation of hematopoietic progenitors in JCML. In serum-deprived...

We have studied the effects of medium conditioned by the human progranulocytic leukemia cell line, HL-60, on the subsequent growth of new inocula of HL-60 cells. When HL-60 cells were cultured at high cell density, optimal growth rate occurred in liquid suspension and confluent colony growth was observed in viscous medium without the addition of conditioned medium. However, when cells were cult...