[IE and IgG antibodies against flavonoids following therapy with flavonoid-containing drugs].

During treatment with flavonoid drugs a number of patients developed adverse reactions such as fever, various skin eruptions and intravascular hemolysis. The appearance of flavonoid-specific IgE and IgG antibodies and its possible relation to the observed side effects was studied on a total of 168 individuals treated with flavonoid drugs: 71 patients received troxerutin (Venoruton) parenterally to improve tolerance of radiation therapy, 12 patients were treated intravenously with silymarin (Legalon) for amanita intoxication and 77 patients received various flavonoid drugs for other indications. Flavonoid treatment often induced specific IgG antibodies and less frequently IgE antibodies. After short treatment IgE antibodies were more frequently detected than after treatment of longer duration which nearly always induced IgG antibodies. Patients with hemolysis had the highest IgG titers. In cases with fever and skin eruptions no correlation with antibody titers became evident. Antibody production in patients undergoing radiation therapy appeared to be lower than in non-irradiated patients. Both the IgE and IgG antibody test show a remarkable cross-reactivity between four different flavonoids. Prospective studies will be necessary to decide whether or not this method for the detection of anti-flavonoid antibodies will be suitable for recognizing increased risk of side reactions upon reexposure to flavonoid drugs.