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Infect. Immun., 04 1996, 1314-1320, Vol 64, No. 4
CA Derrico and KJ Goodrum
The existence of interleukin-12-mediated innate immune responses to group B
streptococci (GBS) was tested by examining T-lymphocyte- independent gamma
interferon (IFN) production in cultured splenocytes from severe combined
immunodeficiency mice. Splenocytes were cultured with killed or living GBS
for 48 h, and then IFN was measured by enzyme- linked immunosorbent assay.
Type III GBS as well as other extracellular bacterial agents of neonatal
sepsis (staphylococci and enterococci) induced IFN production, which was
enhanced by interleukin-2 and was inhibited by neutralizing antibodies to
tumor necrosis factor alpha and to mouse interleukin-12. Interleukin-12
bioactivity was present in conditioned medium from GBS-treated adherent
macrophages. Adherent peritoneal macrophages and bone marrow-derived
natural killer cells from severe combined immunodeficiency mice cultured
separately with GBS did not produce IFN, whereas cocultures did produce
IFN. Functional macrophage activation was evident by nitric oxide
production in GBS- treated splenocyte cultures. The results show that
extracellular pathogens such as GBS, similarly to intracellular microbes,
induce macrophage interleukin-12 and tumor necrosis factor alpha, which
promote natural killer cell secretion of IFN, which then enhances innate
phagocyte resistance mechanisms.
Copyright © 1996, American Society for Microbiology
Interleukin-12 and tumor necrosis factor alpha mediate innate production of gamma interferon by group B Streptococcus-treated splenocytes of severe combined immunodeficiency mice
Department of Biological Sciences, Ohio University, Athens, 45701-2979, USA.
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