Objectives: to describe the values of lymphocyte transformation test (LTT) in patients with delayed drug allergic reaction. Methods: a prospective comparative study, analyzed data of 45 patients with drug allergy treated in the Center of Allergology and Clinical Immunology (Bach Mai Hospital) and National Hospital of Dermatology and Venereology from Dec 2005 to Dec 2006. Results: in patients with drug allergy in general, LTT gives 51.1 percent of positive reaction and 48.9 percent of negative reaction
L T positive rate is 81.82 percent for delayed drug allergic reaction and 21.74 percent for rapid drug allergic reaction (p0.001). LTT of delayed drug allergic reaction is likely to be 16.2 times higher than that of rapid drug allergic reaction (p0.001). Conclusions: LTT gives high rate of positive reaction in delayed drug allergic reaction, much higher than that in rapid drug allergic reaction.