Clinical efficacy and safety of a depigmented and glutaraldehyde polymerized therapeutic vaccine of Parietaria judaica.

BACKGROUND The inhalation of Parietaria judaica pollen is a common cause of allergic respiratory diseases in the Mediterranean area. The objective of this study was to investigate the safety and clinical efficacy of a chemically modified (depigmented and glutaraldehyde-polymerized) vaccine of Parietaria judaica. METHODS AND RESULTS Thirty patients with a well-documented clinical history of seasonal rhinitis and clinical sensitivity to Parietaria judaica pollen were included in a randomized trial during 12 months. The study was conducted following good clinical practices and appropriate consent forms were signed. Patients were divided into 2 groups of 15 individuals; group A received the modified extract and group C did not receive specific immunotherapy. Any adverse event was recorded to assess safety. Symptom scores, symptomatic medication use and the results of specific nasal challenges (before and after 12 months of treatment) were recorded to evaluate clinical efficacy. The treatment schedule consisted of an incremental phase of 5 injections and a maintenance dosage of 0.5 ml per month. Each patient received 14 injections during this period. All the patients completed the trial and no adverse reactions related to immunotherapy were recorded. A significant difference (p < 0.001) in symptom scores and overall use of symptomatic medication was observed between the two groups, being both scores lower in group A. No significant differences in nasal sensitivity existed before treatment among the 2 groups. However, after 12 months, a significant difference (p < 0.05) was observed only in group A patients, who showed a significant improvement in specific nasal challenges. CONCLUSIONS Immunotherapy with depigmented and glutaraldehyde-polymerized extract of Parietaria judaica pollen is safe and effective to treat patients with allergic rhinitis and clinical sensitivity to this pollen.