Evaluation of the drug-induced lymphocyte stimulation test for diagnosing mesalazine allergy

Background/Aims: Mesalazine is an effective drug for treating ulcerative colitis (UC), but causes allergic symptoms in a few cases. Therefore, the objective of this study was to evaluate the usefulness of the drug-induced lymphocyte stimulation test (DLST) for the diagnosis of mesalazine allergy. Methods: Patients with UC treated with mesalazine with or without a history of associated adverse events (AEs) were enrolled at Kyorin University Hospital from July 2016 to April 2017. Results: The DLST was performed in 104 patients with UC, of which 24 had a history of AEs due to mesalazine treatment. The control value of DLST was 337.4 +/- 296.3 counts per minute (cpm) in the AE(+) group and 408.0 +/- 371.9 cpm in the AE(-) group. The measured value of DLST was 578.8 +/- 424.7 cpm in the AE(+) group and 476.5 +/- 471.8 cpm in the AE(-) group. The stimulation index (SI) was 243.9%+/- 291.1% in the AE(+) group and 119.8%+/- 53.0% in the AE(-)group. The SI value and DLST positivity were significantly higher in the AE(+) group than in the AE(-) group (P=0.030 and P=0.029, respectively). The test sensitivity and specificity were 0.240 and 0.805, respectively, and the false-positive and false-negative rate was 0.195 and 0.760, respectively. Conclusions: The DLST for mesalazine showed low sensitivity and high specificity, suggesting that it may be useful for the definitive diagnosis of allergy to mesalazine.