Lymphocyte transformation tests and suspected drug allergy

The problems of confirming that a suspected drug allergy exists and which of the administered drugs is the allergen were studied in 43 patients in whom such a diagnosis was considered. Heparinized whole blood was drawn from each patient and 1 ml. aliquots of the supernatant leucocyte-rich plasma were cultured for 3 to 5 days. Individual drugs were added to cultures at the start of incubation. Thymidine3H was added and the incorporated radioactivity measured. Control cultures were done concurrently. Twelve patients had increased thymidine uptake by their drug-treated cells (positive lymphocyte transformation tests). Five patients with positive tests had them repeated. Thymidine uptake decreased with time after the suspect drug was stopped and all the tests eventually became negative. The lymphocyte transformation test appears to be clinically useful for some patients and can confirm suspected drug allergy at times. Its further development appears warranted.