title: Induction of human gamma interferon by protein A from Staphylococcus aureus.
abstract: Protein A from Staphylococcus aureus (SpA) has been observed to stimulate the production of human gamma interferon (HuIFN gamma) by peripheral blood mononuclear cells (MNC). Dose-dependent experiments showed donor-to-donor variation in the concentration of SpA required for maximum IFN production although 50 micrograms/ml consistently produced near peak IFN gamma titers for each donor. Kinetic studies revealed that peak IFN gamma production occurred 24 hr after SpA stimulation. Physicochemical and antigenic characterization showed that SpA-induced IFN possessed the characteristics of IFN gamma in that it was inactivated by treatment at pH 2, heating at 56 C and anti-HuIFN gamma serum but not by anti-HuIFN alpha serum. Further studies showed tha maximum IFN gamma production could be achieved by stimulating 5 x 10(6) MNC/ml and IFN gamma could be harvested for 3 successive days by removing IFN gamma-containing supernatant fluids and adding fresh medium to stimulated MNC cultures. Preliminary cell fractionation studies suggest that the mononuclear cell that produces IFN gamma after SpA stimulation is a nonadherent lymphocyte that lacks high affinity receptors for sheep erythrocytes and expresses Fc receptors for IgG. Moreover, unlike other mitogen inducers, SpA appears to be less dependent on the presence of macrophages for IFN gamma production.
mesh_terms: D006801:Humans; D007369:Interferon Inducers; D007372:Interferons / Q000096:biosynthesis*; D007700:Kinetics; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D011961:Receptors, Fc / Q000032:analysis; D012397:Rosette Formation; D013205:Staphylococcal Protein A / Q000494:pharmacology*
chemical_list: D007369:Interferon Inducers; D011961:Receptors, Fc; D013205:Staphylococcal Protein A; D007372:Interferons