Effects of serum fractions on the growth of mononuclear phagocytes

Specificity of action of colony-stimulating factors in the differentiation of granulocytes and macrophages

Four colony-stimulating factors (CSFs) (M-CSF, GM-CSF, Multi-CSF and G-CSF) can each stimulate the production of macrophages from progenitor cells in murine bone marrow or fetal liver. However, they differ in their relative selectivity for macrophage progenitor cells and in their dose-response characteristics for stimulating macrophage progenitors relative to other progenitors. It is unresolved whether distinct subsets of progenitor cells exist with a unique responsiveness to one or other CSF or whether the macrophages produced by different CSFs are all functionally equivalent. However, it is shown here that various CSFs can generate from blast progenitor cells an intermediate macrophage progenitor cell whose growth is specifically inhibited by a substance in lectin-stimulated spleen cell-conditioned media. It is also shown that, for at least one myelomonocytic leukaemic cell line, differentiation to macrophages and granulocytes can be induced most effectively by G-CSF but not by M-CSF or Multi-CSF. Finally, the involvement of macrophages and macrophage cell lines in the induced production of these CSFs as well as their display of specific receptors for the different CSFs is examined.

Toxoplasma gondii partially inhibits nitric oxide production of activated murine macrophages

Activated macrophages produce nitric oxide (NO) and as such are able to control the multiplication of Toxoplasma gondii. Until now, no reports have described a possible modulation of NO production of macrophages after T. gondii infection. To investigate this possibility, murine blood monocyte-derived and peritoneal macrophages were activated in vitro with interferon-gamma and lipopolysaccharide and infected with T. gondii and Trypanosoma cruzi, and NO production was evaluated. NO was produced by monocyte-derived macrophages only if cultured in the presence of macrophage-colony-stimulating factor. Monocyte-derived or peritoneal macrophages infected with T. gondii presented a significant reduction in NO production. NO production inhibition was not detected after T. cruzi infection. Macrophages infected with higher T. gondii/macrophage ratios presented lower NO production. Furthermore, only viable T. gondii could cause partial inhibition of NO production. In macrophages activated 24 h before the interaction, partial inhibition was detected after 3 h of infection and continued for 48 h. In macrophages activated immediately after the interaction, partial inhibition was not detected at 12 h, but was observed at 24 h. T. gondii-infected macrophages present lower inducible nitric oxide synthase expression as assayed by immunofluorescence. T. gondii did not develop in monocyte-derived macrophages producing NO, but were not totally eliminated. These results demonstrate that T. gondii infection partially inhibits NO production by murine macrophages, suggesting that a deactivating macrophage mechanism may be used for better survival into phagocytic cells.

Use of the Pannell-Milstein roller bottle apparatus to produce high concentrations of the CSF-1, the mouse macrophage growth factor

A simple roller bottle apparatus for growing B cell hybridomas in dialysis tubing yields high concentrations of monoclonal antibodies (Pannell and Milstein, J. Immunol. Methods (1992) 146, 43-48). Here we describe an adaptation of this apparatus for the simple production of high concentrations of the mouse macrophage specific growth factor, CSF-1. This apparatus appears to have general applicability for the production of other secreted cytokines.

Optimal conditions for proliferation of bone marrow-derived mouse macrophages in culture: the roles of CSF-1, serum, Ca2+, and adherence

A method is described for the analysis of [3H]-thymidine incorporation in microtitre cultures of bone marrow-derived mouse macrophage responding to macrophage colony-stimulating factor (CSF-1). [3H]-thymidine incorporation depends on cell density, culture medium, and the concentration of CSF-1 and serum, but is independent of Ca2+. Bone marrow-derived macrophages are strongly adherent, but adherence can be dissociated from [3H]-thymidine incorporation.