Natural killer T cells expressing IFN-γ and IL-4 in lesional skin of atopic eczema

Background: The inflammation of atopic eczema (AE) is orchestrated not only by T cells predominantly but also B cells, eosinophils and dendritic cells. Recently, a role of invariant natural killer T (NKT) cells has been reported in bronchial asthma and allergy. Natural killer T cells express a restricted repertoire of T-cell receptor alpha/beta and produce interferon (IFN)-gamma and/or interleukin (IL)-4 upon activation. Aim of the study: To determine the presence of NKT cells in lesional AE skin in comparison with other eczematous disorders and to analyse their cytokine expression. Methods: Immunofluorescence stainings were carried out using antibodies recognizing NKT cells, CD3+ and CD4+ cells, IFN-gamma and IL-4. Results: Natural killer T cells have been detected in small numbers in the majority of AE specimens as well as in atopy patch test (APT) reactions, allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). In AE, the proportion of NKT cells among CD3+ cells was approximately 5%. NKT cells expressed both IFN-gamma and IL-4 in AE, APT and ACD but predominantly IFN-gamma in ICD. Conclusion: Natural killer T cells are part of the inflammatory infiltrate of AE as well as APT, ACD and ICD, suggesting a pathogenic role of NKT cells in eczematous skin disorders. The pattern of IFN-gamma and IL-4 cytokine expression by NKT cells varied depending on the type of eczematous disease.