Endotoxin-induced gamma interferon production: Contributing cell types and key regulatory factors

Tushar K. Varma, Cheng Y. Lin, Tracy E. Toliver-Kinsky, Edward R. Sherwood

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

Gamma interferon (IFN-γ) is an important mediator of endotoxin (lipopolysaccharide [LPS])-induced immune responses. However, the specific cell types that produce IFN-γ in response to LPS and the cellular factors that regulate LPS-induced IFN-γ production have not been fully determined. The present studies were undertaken to characterize the cell populations that produce IFN-γ after LPS challenge in the spleens of mice and to determine the regulatory factors that modulate LPS-induced production of IFN-γ. Our studies show that the levels of splenic IFN-γ mRNA and protein production peak at 6 and 8 h, respectively, after systemic LPS challenge. Approximately 60% of IFN-γ-producing cells are natural killer (NK) cells (CD3-DX5+) and 25% are NKT cells (CD3+DX5+). Most of the remaining IFN-γ producing cells are T cells (CD3+DX5-), macrophages, and dendritic cells. Functionally, interleukin-12 (IL-12) is the major IFN-γ-stimulating factor after LPS challenge, with costimulation provided by IL-15, IL-18, and B7 proteins. IL-10 is a major inhibitor of LPS-induced IFN-γ production. Unlike intact heat-killed gram-negative and gram-positive bacteria, the class II major histocompatibility complex did not play a functional role in LPS-induced IFN-γ production. LPS is a potent stimulus for splenic IL-10, IL-12 p40, and IL-15 mRNA expression, whereas IL-12 p35 and IL-18 mRNAs, as well as B7 proteins, are constitutively expressed in the mouse spleen. Of the factors studied, IL-18 serves as the most potent costimulus with IL-12 for IFN-γ production, followed by IL-15 and B7 proteins. These data demonstrate that NK cells and NKT cells are the most abundant IFN-γ-producing cells in the mouse spleen after LPS challenge and that IL-10 and IL-12 are key functional regulators of LPS-induced IFN-γ production.

Original languageEnglish (US)
Pages (from-to)530-543
Number of pages14
JournalClinical and Diagnostic Laboratory Immunology
Volume9
Issue number3
DOIs
StatePublished - 2002

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Clinical Biochemistry
  • Microbiology (medical)

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