Local anaesthetics are known to elicit T-cell reactions after epicutaneous application, namely contact dermatitis. In addition, adverse reactions like urticaria and angioedema are rather common after submucosal or subcutaneous injection. The pathogenesis of these side-effects, which appear frequently hours after application, is unknown, but thought to be not immunoglobulin E-mediated, since immediate skin tests are mostly negative.
We investigated whether patients who developed urticaria and angioedema after subcutaneous application have a T-cell sensitization to local anaesthetics, which might be responsible for the symptoms.
Twenty patients with generalized and/or local cutaneous reactions after LA were examined with intradermal testing using a standard panel of six LAs and patch testing using between seven and nine LAs in vaseline and four LAs in PBS. In 10 patients, a lymphocyte transformation test (LTT) was performed.
Only 2/20 patients had an immediate skin reaction (positive intradermal test), whereas 6/20 patients had a positive delayed skin reaction (positive patch test). In 6/10 subjects the LTT was positive.
Delayed appearance of urticaria and angioedema after subcutaneous application of local anaesthetics may be related to a T cell- mediated sensitization, which might be detected by patch testing or LTT.