Cellular Tests for the Evaluation of Drug Hypersensitivity

The diagnosis of drug hypersensitivity reactions (DHR) is complex, with many potential pitfalls. Although the use of clinical history and skin testing can be valuable, drug provocation testing (DPT) remains the gold standard for many DHR. However, DPT carries some potential risk and should not be performed for severe reactions. There is therefore a general consensus on the need to improve in vitro tests to achieve safe and accurate diagnosis of DHR. A range of in vitro approaches can be applied depending on the type of reaction and the immunological mechanism involved, i.e. IgE- or T-cell-mediated. However, commercially available tests only exist for a handful of drugs, and only for drugs that provoke IgEmediated DHR. Of the cellular tests that focus on the identification of the culprit drug, the best validated is the basophil activation test used for evaluating IgE-mediated reactions. For T-cell-mediated DHR, the lymphocyte transformation test and enzyme-linked immunosorbent spot appear to be the most promising. However, these tests often show low sensitivity. Despite their current drawbacks, in vitro tests can complement in vivo testing and further work in this area will be crucial to improve our current arsenal of tools for the detection and assessment of DHR. For this, the use of appropriate and relevant drug metabolites as well as other factors that can amplify the cell response as well as the use of multiple tests in concert key to improving in vitro diagnosis. Such improvements will be crucial to diagnose patients with severe reactions for whom DPT cannot be performed.