CD40 expression in atopic dermatis (AD) skin lesions and on peripheral blood cells from AD patients was determined and correlations between CD40+ cells and AD disease severity were examined. The nature of CD40+ cells included CD1a+ and CD11b+ antigen processing cells (APCs). A correlation between serum PARC and IgE levels and the number of CD40+ cells in AD skin lesions was found. These findings suggest that CD40 is up-regulated in APCs and that strategies modulating CD40+ cells may be useful in AD patients (Oflazoglu, E. et al. Eur J Dermatol 2008, 18[5]: 527-533).