Mice lacking granulocyte colony-stimulating factor (G-CSF) were generated by targeted disruption of the G-CSF gene in embryonal stem cells. G-CSF-deficient mice (genotype G-CSF-/-) are viable, fertile, and superficially healthy, but have a chronic neutropenia. Peripheral blood neutrophil levels were 20% to 30% of wild-type mice (genotype G- CSF+/+) and mice heterozygous for the null mutation had intermediate neutrophil levels, suggesting a gene-dosage effect. In the marrow of G- CSF-/- mice, granulopoietic precursor cells were reduced by 50% and there were reduced levels of granulocyte, macrophage, and blast progenitor cells. Despite G-CSF deficiency, mature neutrophils were still present in the blood and marrow, indicating that other factors can support neutrophil production in vivo. G-CSF-/- mice had reduced numbers of neutrophils available for rapid mobilization into the circulation by a single dose of G-CSF. G-CSF administration reversed the granulopoietic defect of G-CSF-/- mice. One day of G-CSF administration to G-CSF-/- mice elevated circulating neutrophil levels to normal, and after 4 days of G-CSF administration, G-CSF+/+ and G-CSF- /- marrows were morphologically indistinguishable. G-CSF-/- mice had a markedly impaired ability to control infection with Listeria monocytogenes, with diminished neutrophil and delayed monocyte increases in the blood and reduced infection-driven granulopoiesis. Collectively, these observations indicate that G-CSF is indispensible for maintaining the normal quantitative balance of neutrophil production during “steady-state” granulopoiesis in vivo and also implicate G-CSF in “emergency” granulopoiesis during infections.
The role of Rel in the monocyte/macrophage lineage was examined in mice with an inactivated c‐rel gene. Although the frequency of monocytic cells was normal in Rel−/− mice, we show that Rel serves distinct roles in regulating gene expression and immune effector function in different mature macrophage populations. Stimulated Rel−/− resident peritoneal macrophages produced higher than normal levels of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), granulocyte colony‐stimulating factor (G‐CSF) and interleukin‐6 (IL‐6), but tumour necrosis factor‐alpha (TNF‐alpha) production was not induced. Diminished cytotoxic activity exhibited by resident Rel−/− macrophages was consistent with reduced nitric oxide production resulting from impaired up‐regulation of inducible nitric oxide synthase expression. While a similar altered pattern of IL‐6 and TNF‐alpha expression was observed in stimulated Rel−/− peritoneal effusion macrophages, cytotoxic activity, nitric oxide, GM‐CSF and G‐CSF production by these cells was normal. The alternate regulation of certain genes in the two macrophage populations coincided with different patterns of nuclear Rel/NF‐kappaB complexes expressed in normal resident and elicited cells. Collectively, these results establish that Rel is a positive or negative regulator of transcription in macrophages and that Rel has distinct roles in different macrophage populations.
After infection of mice with Listeria monocytogenes, elevated levels of colony-stimulating factors (CSFs) in the serum were quantitated by six different assays: ability to stimulate colony formation, the proliferation of 2 suspension of bone marrow cells (both measuring total colony-stimulating activity), a radioimmunoassay for macrophage-CSF (CSF-1), the WEHI-3B differentiation assay for granulocyte-CSF, and proliferation of 32D-cl-3 and FDC-Pl cell lines (specific for multi-CSF and either multior granulocyte-macrophage-CSFs, respectively). The great bulk of serum colony-stimulating activity represented macrophageand granulocyte-CSFs, with small but measurable amounts of granulocyte-macrophage-CSF. The degree of elevation of serum CSF depended on the infecting dose used and the numbers of bacteria growing in the spleens and livers of the two mouse strains compared, i.e., L. monocytogenes-resistant C57BL/10 and susceptible BALB/cJ. The increase in serum CSFs occurred before the peak in bone marrow granulocyte-macrophage progenitors and before the reduction in bacterial numbers which follows the onset of specific cell-mediated immunity.
Depletion of endogenous gamma interferon (IFN-y) with anti-IFN-y monoclonal antibody resulted in increased numbers of BruceUla abortus in the spleen and liver of infected CBA mice. This increase was accompanied by a decrease in splenomegaly and a lower proportion of macrophages in the spleen. Furthermore, treatment of recipient mice with anti-FN-y antibody blocked the adoptive transfer of resistance with immune T cells. Together, the results indicated that endogenous IFN-y plays an important role in mediating resistance to primary and secondary BruceUla infection.
A survey of various strains of mice showed distinct differences in resistance or susceptibility to Listeria monocytogenes. C57B1, related sublines, NZB, and SJL were resistant to Listeria, whereas BALB/c, CBA, A, DBA/1, C3H, LP.RIII, 129, and WB were susceptible. The gene(s) responsible for resistance and susceptibility to Listeria were studied in detail. C57B16/6, BMO.D2, and B1O.A mice were 100 times more resistant than were BALB/c, CBA, and A. Resistance of the (C57B1/6 x BALB/c)F1 was intermediate between the two parents, suggesting partial penetration of a dominant gene. Backcross studies in which the (C57B1/6 x ratories at the Austin Hospital or the Microbiology Department by strict brother-sister mating. The mice were mostly derived from the Jackson Laboratory, Bar Harbor, Me. (from the colonies of M. Cherry, G.
Resistance and susceptibility to Listeria monocytogenes in mice was found to be related to (i) the innate ability of the nonimmune macrophages to kill or inhibit the growth of the organism during the first 24 to 48 h after infection; and (ii) the time of onset of acquired cell-mediated resistance. Resistant C57BI/6 mice were 10 times more efficient than susceptible BALB/c mice at suppressing the early growth of Listeria in the liver. Furthermore, the onset of acquired immunity occurred 24 to 48 h earlier in C57B1/6 than in BALB/c mice. Acquired immunity was measured by (i) fall in bacterial numbers in spleen and livers of infected mice, (ii) adoptive transfer of immunity to normal mice by using spleen cells from infected mice, (iii) delayed-type hypersensitivity skin testing, and (iv) uptake of tritiated thymidine by lymphocytes in the spleen.
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