Contact hypersensitivity: T-cell based assay

Abstract To develop an in vitro assay that recapitulates the key event of Allergic Contact Dermatitis (ACD), that is the priming of human effector T cells by hapten-presenting dendritic cells (DCs), and then allows for the sensitive detection of chemical allergens, represents a highly desirable goal but also a major challenge. Substantial progress has been made in recent years in the development of T cell-based assays, also referred to as human T Cell Priming Assays (hTCPA). hTCPA classically consists of an autologous mixed DC-lymphocyte reaction (MDLR) using test chemical-loaded DCs, as stimulatory cells, and normal human naive lymphocytes, as responding cells. Combining diverse strategies which (i) boosted the stimulatory capacities of DCs, (ii) bypassed the cellular or molecular brakes that mitigate T cell activation, or (iii) improved the solubilisation of test chemicals in culture media, the most newly-refined hTCPA protocols showed good results to predict the allergenic potential of chemicals. Although current protocols still require further investment to improve usability and to demonstrate their capacity to establish the sensitizing potency of chemicals, there is no doubt that the hTCPA will be of great help in the forthcoming years to support the immunotoxicologic assessment of new or challenging chemicals.