Scratch test, lymphocyte transformation test (LTT) and cellular antigen stimulation test (CAST) in diagnosis of drug allergy

The purpose of this study was to evaluate the diagnostic value of skin scratch tests and two in vitro methods: lymphocyte transforamtion test (LTT) and cellular antigen stimulation test (CAST) in confirming drug allergy. We studied twenty six patients with clinical symptoms such as urticaria medicamentosa, anaphylaxis, exanthema medicamentosum and oedema angioneurticum. 10 patients has shown hypersensitivity reactions to analgetic (aspirin), 12 patients to antibiotics (8 amocxicillin, 4 cephalosporin C) and 5 patients to chemoterapeutic (trimetoprim/sulfamethoxazole). Our preliminary results demonstrate that 63%(5/8) of patients had positive scratch test, 56% (5/9) LTT and 30% (3/10) CAST to aspirin. A postive LTT to antibiotics was found in 25% (2/8) of patients and 14% (1/7) of patients were positive in CAST. There were no positive results in scratch test to antihiotics. All patients (3/3) were positive to chemoterapeutic in scratch test, 40% (2/5) in LTT and 20% (1/5) in CAST. Our results suggest that none of the metods used has a high sensitivity in confirmation of hypersensitivity reactions to drugs.