SEB-Oktapeptide induzieren eine enterotoxinspezifische T-Zellantwort bei atopischer Dermatitis

Background: Staphylococcal enterotoxins have been shown to contribute to cutaneous inflammation in atopic dermatitis. Enterotoxins may both act as superantigens leading to polyclonal T cell activation and as allergens inducing an enterotoxin specific IgE response. The presence of skin-infiltrating enterotoxin-specific T cells in atopic dermatitis has not been shown yet. Since enterotoxins lead to unspecific T cell activation in their function as superantigens, it is not possible to clearly differentiate enterotoxin-(superantigen-) reactive and enterotoxin-specific T cell responses in vitro. Therefore, we have investigated the T cell response to 30 octapeptides spanning the whole amino acid sequence of staphylococcal enterotoxin B (SEB). Due to their structure, a response to those peptides reflects an SEB-specific T cell response. Methods: PBMC derived from patients with atopic dermatitis sensitized to SEB as determined by CAP FEIA and healthy controls were incubated with SEB peptides. The proliferative response was determined using the Vibrant CFDA SE Cell Tracer Assay. Using limiting dilution cultures, peptide-reactive T cell clones were generated from skin and blood of patients who showed a proliferative response to at least one octapeptide. Results: 70% of the patients sensitized to SEB exhibited a proliferative response to at least one peptide. We could identify two peptides which preferentially induced T cell activation. Frequencies of peptide-reactive T cells in the peripheral blood and the skin were rather low compared to classical allergens and ranged between 0.1 and 0.5% of all T cells. Peptide-specific T cell clones were generated from peripheral blood and lesional skin. Stimulation of these T cell clones resulted in only weak proliferation. The T cell clones were mostly CD4-positive and exhibited a THO- or THI-like cytokine profile. Conclusions: These data suggest that an enterotoxin-specific T cell response is present in the skin and blood of patients with atopic dermatitis sensitized to SEB, but this response is rather weak and probably of minor clinical importance in relation to the superantigen-reactive T cell response.