An investigation on in vivo allergenicity of Artemisia annua leaves and stems.

Pollen of Artemisia annua is considered to be one of the most important allergens in autumnal hay fever in China, just as ragweed is in North America. In order to clarify the allergenicity of non-pollen containing components of the plant, Artemisia annua leaves and stems were collected and extracted before pollination time. The extracts of these pollen-free plant components were studied for allergenic activities using skin prick tests, intradermal tests, intranasal challenge and bronchial provocation tests. In 52 subjects sensitive to Artemisia pollen, 92.3% gave positive responses in skin prick tests, 100% gave positive responses in intradermal tests, 66.7% gave positive responses in intranasal challenge and 59.3% gave positive responses in bronchial provocation tests. Negative results to skin prick tests, intradermal tests and bronchial provocation tests were revealed in 30 seasonal asthmatics who gave negative responses to the pollen skin tests. Strict placebo control showed all negative tests in non-atopic adult human volunteers. We concluded that pollen-free plant extracts did have in vivo allergenic activities. Analysis of the plant allergenic components in vitro will be the subject of further studies.

One year observation of immunotherapy for Artemisia hay fever in China: a clinical and immunological study.

A controlled trial of one year immunotherapy was conducted in 50 Artemisia-sensitive hay fever patients (treatment group). From October 1985 to July 1986, all of the treatment group patients received one year regular injection of Artemisia pollen allergen extract totalling 30,000 protein nitrogen units (PNU). For these patients, symptom score indices of the posttreatment 1986 pollination season were compared with those from the pretreatment 1985 season and also with the scores of a similar group of 30 Artemisia-sensitive patients treated only with symptomatic medications during the 1986 season (control group). The 1986 symptom scores to the treatment group were significantly improved and the effective rate was 78%. Immunological study with the Human Basophil Degranulation Test (HBDT) showed a significant decrease in degranulation reactions after immunotherapy. Moreover, The decline of the HBDT positive rate in the treatment group was significantly greater in patients with improved symptoms than patients with unchanged symptoms. No difference was observed in basophil degranulation in those patients tested with a pollen-free plant extract, which was not applied in immunotherapy. The results suggested that immunotherapy could induce desensitization of basophils and that the induction might be allergen specific. Basophil desensitization may play an important role in the mechanism of immunotherapy.