Interleukin-18 correlates with interleukin-4 but not interferon-γ production in lymphocyte cultures from atopic dermatitis patients after staphylococcal enterotoxin B stimulation.

BACKGROUND Staphylococcus aureus (S. aureus) triggers exacerbation of atopic dermatitis (AD) and causes chronic inflammation through the action of various proteins such as staphylococcal enterotoxin B (SEB). SEB has a role in activating interleukin (IL)-18, an important regulator of interferon (IFN)-γ and IL-4, in regards to a therapeutic strategy. OBJECTIVE To determine the correlation of IL-18 level with the IL-4 and IFN-γ level in lymphocyte cultures from AD patients following SEB stimulation. METHOD Twenty patients with AD based on the Hanifin and Rajka criteria and 20 healthy subjects as a control group were selected. A 5 ml blood sample from each subject was taken for lymphocyte culture. The culture was stimulated with SEB for two days and the outcomes were assessed by enzyme-linked immunosorbent assays (ELISA) to evaluate the levels of IL-18, IL-4, and IFN-γ. RESULTS In the AD group, the levels of IL-18, IL-4, and IFN-γ in lymphocyte cultures with SEB were significantly increased compared with non-SEB exposed cells (each p<0.001); similar results were found in the control group. The level of IL-18 was significantly elevated in lymphocyte cultures with SEB stimulation in AD vs. control (p<0.05) and without SEB in AD vs. control (p<0.05). Furthermore, IL-18 levels were significantly correlated with IL-4 levels and score atopic dermatitis (SCORAD) values in AD patients with SEB (r=0.41, p<0.05; and r=0.70, p<0.05, respectively); on the in contrary, there was no correlation between IL-18 and IFN-γ levels (p=0.469). CONCLUSIONS Our results suggest that IL-18 is correlated with increased of IL-4 levels in SEB-stimulated AD lymphocyte cultures.