Immune regulatory mechanisms in allergic contact dermatitis and contact sensitization.
Contact allergy is a very common disease due to an uncontrolled immune response to chemically reactive small molecular compounds penetrating the skin. The reaction is mostly sustained by specific CD8+and CD4+type 1 T lymphocytes, which are recruited at the site of chemical challenge thanks to the expression of specific homing and chemokine receptors. Evidence exists that specialized subsets of T lymphocytes with regulatory function modulate immune responses to haptens by preventing the occurrence of the hypersensitivity reactions in non-allergic individuals exposed to the sensitizer. In addition, the magnitude of the inflammatory reaction in allergic individuals is also tightly regulated not only by the exhaustion/ apoptosis of effector T cells at the site of chemical challenge, but also by the intervention of T-regulatory cells. Most of the T-regulatory cells involved in this process belong to the CD4+ subset, such as the IL-10-producing T cells, namely Tregulatory cells 1, and the CD4+CD25+T-regulatory lymphocytes. In addition, reports suggest the existence of Treg activity among the CD8+ subpopulation. The currently held view is that contact allergies are the consequences of the exaggerated expansion of specific CD8+ effector T lymphocytes due to an impaired development of efficient regulatory T cells.
Cavani
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Laboratory of Immunology, Istituto Dermopatico dell'Immacolata, IDI-IRCCS, Rome, Italy.
D000818:Animals; D017449:Dermatitis, Allergic Contact / Q000276:immunology* / Q000473:pathology; D005786:Gene Expression Regulation; D006241:Haptens / Q000276:immunology*; D006706:Homeostasis; D006801:Humans; D007108:Immune Tolerance; D007114:Immunization; D007801:Langerhans Cells / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism / Q000473:pathology
D006241:Haptens