Evaluation of lymphocyte transformation tests as compared with patch tests in nickel allergy diagnosis.

BACKGROUND The patch test is considered to be the gold standard for diagnosing nickel (Ni) allergy. The lymphocyte transformation test (LTT) can also be used to detect Ni sensitization. However, little is known about the correlation between patch test and LTT reactions to Ni. OBJECTIVE To establish and validate an LTT for Ni sensitization by comparison with patch test reaction and history. METHODS Fifty individuals without self-reported 'Ni allergy' (controls) and 50 patients with self-reported suspicion of Ni allergy were included. A questionnaire-aided history was taken, and patch tests with at least the baseline series and LTTs with various NiSO4 dilutions were performed. RESULTS In the patch tests, 2 of 50 controls and 18 of 50 patients with self-reported suspicion of Ni allergy showed positive reactions to Ni. In the LTTs, 2 of 50 controls and 26 of 50 patients with self-reported suspicion of Ni allergy showed positive reactions to NiSO4 2.5 × 10-5 m, and 2 of 50 controls and 17 of 50 patients with self-reported suspicion of Ni allergy showed positive reactions to NiSO4 1 × 10-5 m. Sixteen of the 18 history-positive and patch test-positive patients (i.e. 88% sensitivity) were also LTT-positive, in contrast to only 2 positive LTT reactors within the 48 PT and history negative individuals (i.e. 96% specificity). [Correction added on 16 February 2017, after first online publication: The preceding sentence has been edited for language and this has been amended in this version.] CONCLUSION: Performing the LTT with optimized stimulating conditions might be a useful additional tool for the diagnosis of Ni allergy if non-sensitized controls are included.