Staphylococcal alpha toxin induces IFN-γ in skin and blood derived T cells of patients with atopic dermatitis

Abstract Rationale Staphylococcus aureus is present on the skin of 80-90% of patients with atopic dermatitis. Staphylococcal alpha toxin is well described as a hemolysin which is able to induce necrosis of different cell types. We aimed to investigate the effects of subtoxic concentrations of alpha toxin on T cells derived from skin and blood of adult patients with atopic dermatitis. Methods T lymphocytes were incubated with alpha toxin. Proliferation was assessed with the Vibrant TM CFDA SE Cell Tracer Assay. IFN-γ was measured by ELISA and by intracellular staining with anti-IFN-γ. Induction of IFN-γ on the RNA level was determined by light cycler PCR. Results Alpha toxin producing S. aureus strains could be isolated from 50% of the patients. Patients who were colonized with toxin producing S. aureus strains had a significantly worse skin condition than patients who were not. Subtoxic concentrations of alpha toxin (10 pg-100 ng/ml) induced proliferation and production of IFN-γ in CD4+ T cells as determined on the mRNA and protein level. Conclusions These data point to the fact that alpha toxin may induce a TH1 like cytokine milieu and may thus promote chronification of eczema in patients with AD.