Granulysin-Based Lymphocyte Activation Test for Evaluating Drug Causality in Antiepileptics-Induced Severe Cutaneous Adverse Reactions.

Aromatic antiepileptic drugs (AEDs) are common causes of cutaneous adverse drug reactions, which range from morbilliform drug eruption to life-threatening severe cutaneous adverse reactions, including drug reaction with eosinophilia and systemic symptoms, Stevens‒Johnson syndrome, and toxic epidermal necrolysis. Different in vitro methods for identifying the culprit drugs have been developed; however, it is particularly challenging for Stevens‒Johnson syndrome-toxic epidermal necrolysis. In this study, we enrolled 63 patients (39 with Stevens‒Johnson syndrome-toxic epidermal necrolysis, 13 with drug reaction with eosinophilia and systemic symptoms, and 11 with morbilliform drug eruption) and 30 tolerant controls to examine the performance of lymphocyte activation tests by measuring the expression of granulysin, granzyme B, and IFN-γ. Granulysin-based lymphocyte activation tests displayed the best sensitivity and specificity to identify the causality: 73.9% sensitivity and 96.7% specificity for carbamazepine and 68.2% sensitivity and 96.7% specificity for phenytoin. Oxcarbazepine and lamotrigine show weak antigenicity. Granulysin-based lymphocyte activation tests expanded predominantly memory cytotoxic T lymphocytes with characteristics of drug-specific T-cell receptor, major histocompatibility complex I dependence, and cross reactivity to different aromatic AEDs. Among 29 follow-up patients, 28 alternatively used nonaromatic AEDs, and none developed cutaneous adverse drug reactions. Our data suggest that granulysin-based lymphocyte activation tests represent in vitro cytotoxic T-lymphocyte memory response to offending drugs and are useful to confirm drug causality of AED-induced severe cutaneous adverse reactions. Implementing these tests will improve the AED-induced severe cutaneous adverse reactions prevention and clinical care.