In vitro tests for Drug Hypersensitivity Reactions. An ENDA/EAACI Drug Allergy Interest Group Position Paper
Potential drug allergic reactions are frequently encountered by healthcare professionals. It can be difficult to confirm the diagnosis of drug allergy without re-challenging the individual to the drug again. Issues relating to incorrect patient reporting and loss of sensitivity over-time can lead to the unnecessary avoidance of certain drugs and sub-optimal treatment. There is a general consensus on the need for biological tests to establish the nature of culprit agents and to predict immunogenicity.
The immune responses involved in drug allergy are now better understood. As a result there are a growing number of laboratory tests that are capable of evaluating the response to a drug from the blood of an individual thus avoiding the risk of re-exposing them. Most of these tests are performed at a time of clinical stability after the reaction; however, some can be performed at the time of the reaction to confirm that an allergic process is taking place.
Some tests, such as measuring drug specific antibody levels, have been available for clinical use for many years. And in the recent years other cellular tests have been included in the in vitro evaluation of drug hypersensitivity.
In this review we evaluate the evidence for these traditional investigations. In addition we explore modern techniques and the role they may play in future clinical care. This includes discussions about newer drug classes, for example biological agents.
At present many of these tests remain research tools that have only been evaluated in small populations with variable results. In future larger studies in well characterised populations will hopefully lead to commercial systems that are standardised across countries.