Immunoreactive leukotrienes in nettle plants (Urtica urens).

In order to clarify the mechanisms of urtication after contact with stinging plants, nettle (Urtica urens) hair and whole-plant extracts were examined for the presence of leukotriene (LT) B4 and LTC4 by reverse phase high-pressure liquid chromatography (RP-HPLC) and radioimmunoassay (RIA) and for in vitro neutrophil chemotactic activity and histamine contents. Both hair and plant extracts contained high levels of LTB4 and LTC4 by RIA as well as histamine. The presence of LTB4 was supported by RP-HPLC elution profiles and by in vitro chemotaxis. Nettle hairs therefore resemble insect venoms and cutaneous mast cells with regard to their spectrum of mediators.