Herbal medicine and false-positive results on lymphocyte transformation test

In vitro mitogenic activity of 16 herbs and 3 Kampo (herbal medicine) formulae have been reported in experimental studies. It is not known how many herbs and Kampo formulae in total have mitogenic activity. Lymphocyte transformation test (LTT) is generally utilized to diagnose drug-induced liver injury. In LTT, mitogenic activity is assessed by measuring 3H-thymidine incorporation. The objective of the present study was to determine which herbs and which Kampo formulae caused false-positivity on LTT. We examined 2496 summaries of all admission records from 1979 to 1999 in our department. We selected patients in whom liver injuries were diagnosed as definitely unrelated to Kampo medication. In these patients, LTT was performed for some herbs contained in the suspect Kampo medicines, resulting in positive LTT for 17 herbs: Evodiae Fructus (Goshuyu), Zizyphi Fructus (Taiso), Ginseng Radix (Ninjin), Zingiberis Rhizoma (Shokyo), Hoelen (Bukuryo), Aconiti Tuber (Bushi), Angelicae Radix (Toki), Cnidii Rhizoma (Senkyu), Rehmanniae Radix (Jio), Ephedrae Herba (Mao), Anemarrhenae Rhizoma (Chimo), Cinnamomi Cortex (Keihi), Bupleuri Radix (Saiko), Artemisiae Capillari Spica (Inchinko), Persicae Semen (Tonin), Moutan Cortex (Botanpi) and Paeoniae Radix (Shakuyaku). These results were considered false-positive, because the results were observed in the "definitely unrelated" patients. Mitogenic activity inherent to some herbs and Kampo formulae may sometimes cause false-positivity on LTT in clinical situations. These examples suggest that LTT for Kampo formulae may be unreliable as a diagnostic method for drug-induced liver injury.