Innate and adaptive immune responses to the major Parietaria allergen Par j 1 in healthy subjects

In this study we wanted to analyse the pattern of the immune response to the Parietaria major allergen Par j 1 in freshly purified peripheral blood mononuclear cell (PBMC) from healthy subjects. We observed that Par j 1 was capable of inducing IFN-γ production by CD3− and CD16+/CD56+ cells exclusively in healthy individuals. Furthermore, a multiparametric analysis allowed us a better definition of two IFN-γ-Par j 1 specific populations (IFN-γdim and IFN-γhigh) characterized by the presence of different proportions of NKT and NK cells. We also identified the concomitant presence of a subset of IL-10+ NK cells. Moreover, CFSE staining showed that the Par j 1 preferentially induced the proliferation of CD3−/CD56+/CD335+ cells. Finally, a subset of CD4+/CD25+/FoxP3+/IL-10− T cells was identified. The result of this pilot study suggest that during a tolerogenic response, the major allergen of the Parietaria pollen works as an activator of both the innate and the adaptive human immune system.