Double-blind, placebo-controlled immunotherapy with mixed grass-pollen allergoids: I. Rush immunotherapy with allergoids and standardized orchard grass-pollen extract

Abstract

Forty-five grass pollen-allergic patients were randomly assigned to three groups according to their skin test and RAST sensitivities and the severity of seasonal rhinitis. Eleven patients were treated with placebo (group 1), 19 patients (group 2) were treated with a six-mixed grass-pollen allergoid prepared by mild formalinization with a two-step procedure, and 15 other patients were treated with a standardized orchard grass-pollen extract (group 3). Because of a different immunotherapy schedule, only patients placed in groups 1 and 2 received the extracts in a double-blind fashion. Rush immunotherapy was performed in 3 to 6 days, and the maintenance dose was subsequently administered weekly for 4 weeks and every 2 weeks until the end of the grass-pollen season. During the season, a coseasonal treatment was administered. Systemic reactions occurred during the rush protocol in 36.8% of patients treated with allergoid and 20% of patients who received the standardized extract. Only patients treated with allergoid had systemic reactions during maintenance dose. The reactions observed with the standardized extract were more severe. Total doses of allergoid ranged from 2350 to 13,500 protein nitrogen units. Symptom and medication scores during the peak of the season were analyzed. Patients treated with the standardized allergen had a significant reduction of the number of days of symptoms during the month of June (9.5 ± 6.7 days; p < 0.005) and of medication scores (1.3 ± 1.4; p < 0.01) compared to patients receiving placebo (19.4 ± 8.1 days; medication score, 2.8 ± 2.1). Patients treated with allergoid also had a significant reduction of symptomatic days (11.3 ± 7.6; p < 0.01) and medication score (1.7 ± 1.5; p < 0.05) compared to patients receiving placebo. There was no significant difference between the two treated groups. The mean skin prick test end point was significantly reduced in both treated groups after immunotherapy and unchanged in the placebo-treated group. Serum grass-pollen IgG measured by solid-phase radioimmunoassay with Staphylococcus aureus protein A was significantly increased after immunotherapy in both treated groups and remained unchanged in the placebo-treated group. This study demonstrates that both a standardized allergen extract and a formalinized allergoid are effective in the treatment of grass-pollen rhinitis.