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

Summary Background The patch test is considered to be the gold standard for diagnosing nickel ( N i) allergy. The lymphocyte transformation test ( LTT ) can also be used to detect N i sensitization. However, little is known about the correlation between patch test and LTT reactions to N i. Objective To establish and validate an LTT for N i sensitization by comparison with patch test reaction and history. Methods Fifty individuals without self‐reported ‘ N i allergy’ (controls) and 50 patients with self‐reported suspicion of N i allergy were included. A questionnaire‐aided history was taken, and patch tests with at least the baseline series and LTT s with various N i SO 4 dilutions were performed. Results In the patch tests, 2 of 50 controls and 18 of 50 patients with self‐reported suspicion of N i allergy showed positive reactions to N i. In the LTT s, 2 of 50 controls and 26 of 50 patients with self‐reported suspicion of N i allergy showed positive reactions to N i SO 4 2.5 × 10 −5 m , and 2 of 50 controls and 17 of 50 patients with self‐reported suspicion of N i allergy showed positive reactions to N i SO 4 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 N i allergy if non‐sensitized controls are included.