Modulation of Skin Norepinephrine Turnover by Allergen Sensitization: Impact on Contact Hypersensitivity and T Helper Priming

The information gathered by dendritic cells during the innate immune response is determinant for the type and strength of the adaptive response. We showed that the sympathetic neurotransmitter norepinephrine influences dendritic cell migration and T helper priming via α- and β-adrenoceptors. Others have shown that Langerhans cells also express mRNA for β1-, β2-, and α1 A -adrenoceptors and that catecholamines may inhibit the antigen-presenting capability via β2-adrenoceptors. Here we report that oxazolone, which induces a predominant T-helper-1-type contact hypersensitivity response, but not fluorescein isothiocyanate, which induces a prevailing T-helper-2-type response, inhibits the local norepinephrine turnover in the skin of mice during the first 8 h of sensitization. Oxazolone also induced higher expression of the inflammatory cytokines interleukin-1 and interleukin-6 mRNA in the skin. Lack or blockade of these cytokines as well as inhibition of prostaglandin synthesis, however, did not influence the oxazolone effect. Only the nonspecific anti-inflammatory steroid dexamethasone could neutralize the effect of oxazolone. Furthermore, fluorescein isothiocyanate but not oxazolone sensitization in the presence of the specific β2-adrenoceptor antagonist ICI 118,551 enhanced the consequent contact hypersensitivity response as well as the production of T helper 1 cytokines in draining lymph nodes; conversely T helper 2 cytokines were not affected. Thus, the extent of T helper 1 priming in the adaptive response to a sensitizing agent seems to depend also on its ability to modulate the local sympathetic nervous activity during the innate immune response.