title: Staphylococcal enterotoxin B inhibits the production of interleukin-4 in a human mast-cell line HMC-1.
abstract: Staphylococcal enterotoxins belong to the recently characterized group of immunocytotropic bacterial superantigens that are potent mitogens for human T cells. Superantigens are presented, but without intracellular processing, to T cells by monocyte/macrophages, Langerhans' cells and keratinocytes via the class II major histocompatibility complex (MHC) molecules. Superantigens have been demonstrated to act as potent inducers of several proinflammatory cytokines in the antigen-presenting cells such as interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha). As mast cells participate in the pathogenesis of several inflammatory skin disorders such as atopic dermatitis (AD), which is often aggravated by staphylococcal infections, we studied the effect of staphylococcal enterotoxin B (SEB) superantigen on the histamine release and IL-4 expression in a human mast-cell line (HMC-1). Incubation of SEB (50 micrograms/ml) with HMC-1 cells for 45 min, could not induce any histamine release. The HMC-1 cells were also stimulated with various concentrations of SEB (0, 1, 10, 20, 50 micrograms/ml) for 1, 2, 3 and 4 days. Clear dose-dependent inhibition of IL-4 protein production and release was observed on day 4 without any observed effect on cell viability. Compared with unstimulated HMC-1 cells, after 50 micrograms/ml SEB stimulation, the IL-4 mRNA levels decreased steadily in the 2, 6, 18 and 24 hr samples in repeated experiments as measured with the reverse transcription polymerase chain reaction (RT-PCR) method. In comparison, a biphasic decrease in TNF-alpha expression was found. Our results show that an human leukaemic mast cells, superantigen stimulation downregulates the production of IL-4.
authors.affiliation: Department of Dermatology, Kuopio University Hospital, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Ackermann
authors.forename: J
authors.initials: J
authors.lastname: Pelkonen
authors.forename: I T
authors.initials: IT
authors.lastname: Harvima
mesh_terms: D015550:Cell Degranulation / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology; D004768:Enterotoxins / Q000276:immunology*; D006636:Histamine Release; D006801:Humans; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000235:genetics; D008407:Mast Cells / Q000276:immunology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013211:Staphylococcus aureus / Q000276:immunology*; D018089:Superantigens / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
chemical_list: D004768:Enterotoxins; D012333:RNA, Messenger; D018089:Superantigens; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; C031818:enterotoxin B, staphylococcal