Early Events in the Induction Phase of Contact Sensitivity

After allergen application to skin, there is enhanced class II major histocompatibility complex antigen expression, as well as enhanced T-cell–stimulatory function by epidermal Langerhans cells (LC). In this study, we investigated the early changes in the epidermal cytokine profile using a sensitive reverse transcriptase PCR technique to determine whether cytokines may be related to LC activation. We found that, on the mRNA and protein level, changes in the epidermal cytokine pattern caused by allergens in the induction phase of contact sensitivity are distinct from those caused by irritants or tolerogens. The earliest of the changes is the LC-derived interleukin (IL) lβ mRNA signal strength that is increased within 15 min of allergen painting.