Aqueous allergenic extracts of Parietaria judaica contain non proteic compounds critical for DC maturation and production of Th2-related cytokines independently from specific sensitization. (37.17)

Abstract The pollen of Parietaria judaica (Pj) is a main source of allergenic sensitization in Mediterranean area and in other countries. Recently, many evidences suggests that pollens are a complex mixture of different compounds able to affect the immune response. Here we show that aqueous extracts of whole pollen, but not protein extracts or purified allergens of Pj, induce maturation of human DC prepared from peripheral blood from both sensitized and non sensitized donors. As assessed by flow cytometry, these cells expressed high levels of HLA-DR, CD80, CD54 and CD86 and were able to strongly stimulate allogenic T cells in MLR. Moreover, the whole-pollen extract induce a strong production of IL-10 and IL-13 and expression of several chemokine receptors. The protein extract, as well as the purified allergen failed to induce DC maturation and stimulated only a weak production of IL-4. These findings were independent from the sensitization status of the donors. Taken together, these results further indicate that pollens should not to be considered merely as a carrier of allergenic proteins but, rather, they are complex antigens and affect directly the immune response in sensitized and non sensitized individuals. Therefore, we propose to reconsider the importance of pollens as complex antigens and to further exploit their ability to elicit different immune responses other than classical IgE-mediated reactions.