Differential secretion of interleukin-12 (IL-12) subunits and heterodimeric IL-12p70 protein by CD-1 mice and murine macrophages in response to intracellular infection by Brucella abortus.
The secretion of interleukin-12 (IL-12) following intracellular infection with virulent Brucella abortus strain 2308 was investigated in CD-1 mice and in CD-1 cultured peritoneal macrophages. Bioactive IL-12p70 and free non-immunoactive p40 subunits (IL-12p40) were determined by enzyme-linked immunosorbent assays. In CD-1 mice, B. abortus 2308 was a potent inducer of IL-12p40 (maximum levels were 5.9 and 3.4 ng/ml in sera and spleen homogenates, respectively). Secretion of IL-12p70 was also demonstrated in vivo, although at much lower levels (216.6 and 198.9 pg/ml in sera and spleen homogenates, respectively). Production of IL-12 over the first 7 days after infection was accompanied by active multiplication of B. abortus in the spleens of infected mice. CD-1 cultured peritoneal macrophages secreted only IL-12p40 (878.4 pg/10(7) macrophages) in response to B. abortus infection and no production of IL-12p70 was observed. In contrast, CD-1 peritoneal macrophages secreted detectable amounts of IL-12p70 (16.2 pg/10(7) macrophages) in response to purified lipopolysaccharide (S-LPS) from B. abortus 2308. The macrophages also secreted significant amounts of interferon-gamma (IFN-gamma) (520.1 pg/10(7) macrophages) in response to intracellular B. abortus. These results indicate that B. abortus 2308 is not a potent inducer of IL-12p70 production, whereas purified S-LPS from B. abortus 2308 induces the secretion of this bioactive form of IL-12 in cultured peritoneal macrophages. CD-1 peritoneal macrophages were able to secrete IFN-gamma, as well as high amounts of IL-12p40, in response to intracellular infection by B. abortus.
Fernández-Lago
Luis
L
Rodríguez-Tarazona
Elisa
E
Vizcaíno
Nieves
N
D000818:Animals; D002003:Brucella abortus / Q000276:immunology*; D002006:Brucellosis / Q000276:immunology* / Q000382:microbiology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis*; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D013154:Spleen / Q000276:immunology
D018664:Interleukin-12; D007371:Interferon-gamma