The Journal of immunology : official journal of the American Association of Immunologists
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It has been shown that low concentrations of E. coli lipopolysaccharides (LPS) greatly and selectively stimulate phagocytosis and related functions in mouse bone marrow-derived macrophages. Culture in the presence of 50 ng/ml LPS induced on average a 10-fold enhancement of phagocytosis of IgG-coated sheep erythrocytes. Activation was in two stages--a small increase observed during the first 8 to 12 hr, and the major increase noted between 16 and 24 hr. ⋯ Beta-glucuronidase, beta-galactosidase, alkaline phosphodiesterase, and aminopeptidase were unchanged and NAD nucleosidase was markedly decreased after LPS treatment. 5'-Nucleotidase and glucosamine uptake were undetectable both in control and LPS-stimulated cells. LPS treatment induced a significant increase in cell-associated protein, but did not result in cell proliferation or increased cell loss as shown by the DNA content that remained constant. LPS-induced changes were dependent on de novo protein synthesis; cycloheximide prevented enhancement of phagocytosis, Fc receptor capacity, and colony formation.