T-cell reaction to local anaesthetics: relationship to angioedema and urticaria after subcutaneous application - patch testing and LTT in patients with adverse reaction to local anaesthetics

Background Local anaesthetics are known to elicit T-cell reactions after ep icutaneous application, namely contact dermatitis. In addition, adverse rea ctions like urticaria and angioedema are rather common after submucosal or subcutaneous injection. The pathogenesis of these side-effects, which appea r frequently hours after application, is unknown, but thought to be not imm unoglobulin E-mediated, since immediate skin tests are mostly negative. Objectives We investigated whether patients who developed urticaria and ang ioedema after subcutaneous application have a T-cell sensitization to local anaesthetics, which might be responsible for the symptoms. Methods Twenty patients with generalized and/or local cutaneous reactions a fter LA were examined with intradermal testing using a standard panel of si x LAs and patch testing using between seven and nine LAs in vaseline and fo ur LAs in PBS. In 10 patients, a lymphocyte transformation test (LTT) was p erformed. Results Only 2/20 patients had an immediate skin reaction (positive intrade rmal test), whereas 6/20 patients had a positive delayed skin reaction (pos itive patch test). In 6/10 subjects the LTT was positive. Conclusions Delayed appearance of urticaria and angioedema after subcutaneo us application of local anaesthetics may be related to a T cell-mediated se nsitization, which might be detected by patch testing or LTT.