Résumé : Atopic dermatitis (AD) is a chronic inflammatory skin disease associated with cutaneous hyperreactivity to environmental stimuli, resulting in increased infiltration of inflammatory cells, IgE production and enhanced expression of costimulatory molecules, cytokines and chemokines. CD30, a TNF receptor superfamily member, is a costimulatory molecule expressed on activated T and B cells. A positive correlation between soluble CD30 (sCD30) levels in patient serum and AD disease severity has been described previously. However, the relative frequencies and identities of cells expressing CD30 in AD patients and the relationship between the frequency of CD30 positive cells and serum sCD30 levels with disease severity remained unknown. To address these questions, immunofluorescence analysis of AD skin lesions representing different disease stages, was conducted. In addition to the CD4+ T cells, CD1a+ Langerhans cells and CD8+ T cells were found to express CD30 in AD lesions and the cell numbers correlated with disease severity. FACS analysis of AD patient blood samples revealed expression of CD30 on memory T-cells and a correlation with disease severity was identified. Finally, serum analysis of soluble mediators revealed positive correlations between sCD30, IgE, MDC, TARC and PARC levels with disease severity. Combined, our data provide correlative evidence that CD30+ cells, including Langerhans cells and CD8+ T-cells, may contribute to AD disease severity and that therapeutic strategies targeting CD30+ cells may provide benefit to AD patients.