Epidermal cytokines IL-1 beta, TNF-alpha, and IL-12 in patients with atopic dermatitis: Response to application of house dust mite antigens

Epidermal cytokines such as interleukin (IL)-1 beta, tumor necrosis factor- alpha, and IL-12 have been described to play a crucial role in the inductio n and elicitation phase of allergic contact dermatitis upon exposure to hap tens, In this study we asked whether these cytokines may also play a role i n the epidermis of patients with atopic dermatitis after the application of house dust mite antigens (HDM) to their skin. Epidermal samples were colle cted by scraping healthy appearing skin of atopic patients and healthy indi viduals 8 h after the application of an extract of HDM. Sodium lauryl sulfa te and saline served as controls. Reverse transcriptase-polymerase chain re action was performed for IL-1 beta, tumor necrosis factor-alpha, IL-12 p35, and IL-12 p40. Exposure to HDM led to a significant upregulation of mRNA o f these cytokines in atopic patients only. Whereas IL-1 beta and tumor necr osis factor-alpha also showed an upregulation in part of these patients aft er exposure to the irritant sodium lauryl sulfate, IL-12 p40 mRNA was exclu sively enhanced by the application of the allergen, In contrast to IL-12 p4 0, IL-12 p35 mRNA was not detectable in significant amounts. Interestingly, also in untreated, normal appearing skin of atopic individuals (n = 16), t he levels of these cytokines were higher than in normal individuals (n = 8) , possibly explaining the increased skin irritability of atopic individuals . Finally, comparing epidermal cytokines in the skin of patients who develo ped a positive allergen patch test to those who stayed negative, suggests t hat only expression of IL-1 beta mRNA may be a predictive marker for the de velopment of a positive patch test reaction to HDM.