Immunoregulation of hapten and drug induced immune reactions

Purpose of review: Unbalanced immune responses to haptens lead to a variety of diseases, including allergic contact dermatitis to skin sensitizers and drug induced immune reactions. The occurrence, magnitude and persistence of immune responses are modulated by specialized T cell subsets with regulatory function. The purpose of this brief review is to summarize the recent data on the role of regulatory T cells in the control of hapten mediated diseases. Recent findings: Several subsets of regulatory T cells, including T regulatory cell 1-like lymphocytes, and cutaneous lymphocyte associated antigen ⁺ CD4⁺CD25⁺ regulatory T cells have been isolated from the skin at sites of hapten challenge. Both cell types suppress specific T cell responses to cutaneous sensitizers, such as nickel. Summary: Although data concerning the regulation of drug hypersensitivity are lacking, several reports indicate the role of regulatory T cell subsets in allergic contact dermatitis to haptens. The understanding of their role in hapten diseases and the requirement for their in-vivo and in-vitro expansion appears as a critical step for the development of specific desensitization protocols.