Epicutaneous Application of Protein Antigens Incorporated into Cosmetic Cream Induces Antigen-Nonspecific Unresponsiveness in Mice and Affects the Cell-Mediated Immune Response

Abstract

Background: Protein antigens applied epicutaneously by the patch method induce allergic dermatitis mediated by IgE antibodies in mice and simultaneously significant suppression of Th1-mediated delayed-type hypersensitivity (DTH) reactions. Methods: We developed a method in which protein antigens (calf collagen, elastin, keratin, TNP-substituted mouse Ig) were homogenized with neutral cream. Animals treated epicutaneously with such preparations were tested for contact sensitivity to TNP hapten or DTH hypersensitivity to hemocyanin. Antigen specificity of induced unresponsiveness was tested in vivo in ‘transfer-in’ and ‘transfer-out’ experiments. The influence of skin-induced regulatory cells on in vitro [³H]thymidine uptake by immune cells as well as the possible mode of their action using anticytokine antibodies were tested. Results: Our procedure in which different protein antigens are applied on the skin in the form of cream induces a state of antigen-nonspecific unresponsiveness affecting cell-mediated immune responses in mice. Cream alone has no such effect. Suppression is transferable in vivo by TCR-αβ lymphocytes, while Tγδ cells show no activity. In vitro, lymphoid cells of skin-tolerized mice suppress [³H]-thymidine incorporation by immune cells and this effect can be abolished by adding anti-TGF-β but neither anti-IL-4 nor anti-IL-10 antibodies. Conclusions: Lack of antigen-specifity of unresponsiveness induced by epicutaneous deposition of cream containing protein antigens resembles ‘determinant spreading’ in oral tolerance induced by antigen feeding. This may suggest that similar immunoregulatory mechanisms operate on these two bodily surfaces.