title: Effects of superantigen and lipopolysaccharide on induction of CD80 through apoptosis of human monocytes.
abstract: To investigate the mechanisms underlying superantigen (SAg) stimulation, we analyzed the effect of SAg on monocyte responses with or without lipopolysaccharide (LPS). Addition of gamma interferon (IFN-gamma) to unstimulated cultures induced a marked increase in the number of CD80(+) monocytes, which was inhibited by LPS through the action of interleukin-10. However, CD80(+) monocytes began to increase before IFN-gamma production, observed after 9 h of stimulation with staphylococcal enterotoxin B (SEB). SEB selectively increased the number of apoptotic CD80(-) monocytes, whereas LPS-treated monocytes were resistant to the apoptotic action of SEB. This SEB-induced killing was abrogated by anti-CD95 monoclonal antibody (MAb) ZB4 and anti-CD95 ligand (CD95L) MAb NOK2, suggesting a CD95-based pathway of apoptosis. Furthermore, the numbers of SEB-induced CD80(+) monocytes were partially decreased by anti-CD119 (IFN-gamma receptor) MAb and by anti-CD95L (NOK2) MAb. The CD30 expression of CD27(high) T cells induced by SEB was increased by agonistic anti-CD95 (CH11) MAb. Together, our findings showed that SEB-induced monocyte apoptosis is closely associated with the enrichment of CD80(+) monocytes generated before IFN-gamma production, followed by up-regulation of CD80 by IFN-gamma, and that LPS has negative effects in both cases. These results also suggested that induction of monocyte apoptosis is an important mechanism by which SAg exerts its anti-inflammatory effects.
authors.affiliation: Department of Microbiology and Immunology, Tohoku University School of Dentistry, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: F
authors.initials: F
authors.lastname: Shinohara
authors.forename: H
authors.initials: H
authors.lastname: Takada
authors.forename: H
authors.initials: H
authors.lastname: Rikiishi
mesh_terms: D017209:Apoptosis / Q000276:immunology*; D018122:B7-1 Antigen / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D004768:Enterotoxins / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008213:Lymphocyte Activation; D009000:Monocytes / Q000276:immunology*; D018089:Superantigens / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors
chemical_list: D018122:B7-1 Antigen; D016207:Cytokines; D004768:Enterotoxins; D008070:Lipopolysaccharides; D018089:Superantigens; C031818:enterotoxin B, staphylococcal; D007371:Interferon-gamma