A DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF LOCAL NASAL IMMUNOTHERAPYIN ALLERGIC RHINITIS TO PARIETARIA POLLEN

We assessed the efficacy and safety of local nasal immunotherapy (LNIT ) using an extract in macronized powder form of Parietaria pollen, a v ery important allergenic plant in the Mediterranean and other parts of the world. Twenty-six patients aged 13-37 years, with seasonal allerg ic rhinitis to this pollen, were enrolled in a double-blind placebo-co ntrolled trial, carried out from autumn 1991 to the end of June 1992. They were selected on the basis of a positive skin-prick test, radioal lergosorbent test (RAST) and intranasal challenge to Parietaria antige n. Patients were randomly divided into two groups of 13; the first gro up was given Parietaria antigen, and the second placebo. We recorded m ean weekly symptom scores and drug consumption for 17 weeks during the pollen season in the year 1992, and specific serum-IgE and IgG levels . Three patients in the active group withdrew from the study because o f bronchial symptoms. A significant difference was observed in mean we ekly nasal symptom scores, in drug consumption and in specific nasal t hreshold to Parietaria allergenic extract in the treated and control g roups. No difference was observed in serum IgE and IgG levels. Serum I gE levels rose significantly only in the control group after the polle n season. This study indicates that LNIT may be a useful alternative t o traditional subcutaneous immunotherapy in patients with allergic rhi nitis.