Stimulation of natural interferon-alpha/beta-producing cells by Staphylococcus aureus.
Human peripheral blood mononuclear cells (PBMCs) produced high levels of antiviral activity, as determined by bioassay, when stimulated by Staphylococcus aureus Cowan I (SAC) and E. coli. Specific immunoassays demonstrated the presence of both IFN-alpha and gamma and, for SAC, also low levels of IFN-beta. The frequencies of SAC-induced IF N-alpha-producing cells (IPCs) were up to 1-2 per 10(3) PBMCs. These IPCs expressed the HLA-DR and CD4 antigens but not CD3, CD14, or CD19, thus resembling the natural IFN-alpha-producing cells (NIPC). The SAC was more efficient as IFN inducer when heat killed than when streptomycin inhibited. The SAC was inhibitory to virally induced IFN-alpha responses, in particular when streptomycin inhibited. Both pronase treatment and mechanical disruption of SAC cells abolished their capacity to induce IFN-alpha production. Staphylococcal strains lacking or expressing low levels of protein A (SpA) showed a decreased ability to induce IFN-alpha production. However, purified SpA did not itself induce IFN-alpha. Possibly, SpA together with other bacterial surface proteins is important for the capacity of SAC to induce IFN-alpha production in NIPC.
Svensson
H
H
Department of Veterinary Microbiology, Swedish University of Agricultural Sciences, Biomedical Center, Uppsala, Sweden.
Cederblad
B
B
Lindahl
M
M
Alm
G
G
D002455:Cell Division / Q000187:drug effects; D006801:Humans; D016130:Immunophenotyping; D066298:In Vitro Techniques; D007369:Interferon Inducers; D016898:Interferon-alpha / Q000096:biosynthesis*; D016899:Interferon-beta / Q000096:biosynthesis*; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D013205:Staphylococcal Protein A / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*; D013307:Streptomycin / Q000494:pharmacology; D013314:Stress, Mechanical
D007369:Interferon Inducers; D016898:Interferon-alpha; D013205:Staphylococcal Protein A; D016899:Interferon-beta; D013307:Streptomycin