1. ¹Faculté de Médecine, Université Lyon1, Lyon-Sud, France
2. ²INSERM, U851, Lyon, France
3. ³Université Lyon, IFR 128, Lyon, France
4. ⁴Hospices Civils de Lyon, Immunologie Clinique et Allergologie, CH Lyon-Sud, France

Correspondence: Dr Marc Vocanson, INSERM U851, IFR 128, BioSciences Lyon-Gerland, 21 Avenue Tony Garnier, 69365 Lyon Cedex 07, France. E-mail: marc.vocanson@inserm.fr

Received 27 May 2008; Revised 1 September 2008; Accepted 9 September 2008; Published online 13 November 2008.

Abstract

Allergic contact dermatitis (ACD) is mediated by hapten-specific CD8+ T cells and downregulated by CD4+ T cells. We have recently shown in a model of ACD to weak haptens that priming of IFN-producing CD8+ T cells and the development of skin inflammation could be obtained in mice deficient in CD4+ T cells. Here we show that IFN production by lymph node (LN) cells draining the site of skin sensitization of CD4+ T-cell-deficient mice is a marker of the sensitizing properties of weak haptens. LN cells from mice sensitized as in the classical local lymph node assay (LLNA) were recovered at day 5, then cultured for 20 hours in the presence of submitogenic doses of phytohemagglutinin, and finally tested for the production of IFN. Results show that: (i) production of INF by LN cells was induced by weak and moderate allergens in a dose-dependent fashion; (ii) the magnitude of IFN production paralleled the sensitizing properties of allergens allowing to classify them as moderate or weak haptens; (iii) chemicals without sensitizing properties were unable to stimulate IFN production by LN cells. Therefore, the IFN LLNA appears as a sensitive, specific, and robust assay to detect weak contact allergens.