A double-blind histamine placebo-controlled trial of polymerized whole grass for immunotherapy of grass allergy

Twenty-six patients were recruited for a study of the safety and efficacy of immunotherapy with IPG. They were randomly assigned to two groups based on skin test titrations to grass allergens. One group was treated in a double-blind fashion before the 1982 grass season with 12 weekly injections totaling approximately 48,000 PNU, and the other group was treated with 12 weekly injections of caramelized glucose histamine placebo. Daily symptom and medication score sheets were completed by all patients each day of the grass season. Blocking antibody rose ninefold in the IPG group (p less than 0.007) but was unchanged in the placebo group. There was no significant change in IgE against rye grass group I in either the IPG or the placebo group. Symptom-score mean in the IPG group was 217 +/- 71 (S.E.M.), statistically lower (p less than 0.02) than the mean in the placebo group 496 +/- 117 (S.E.M.). There were no systemic reactions and only minor local reactions. There was no change in routine laboratory tests in either group. Although two prior studies with grass allergen immunotherapy reported efficacy, these studies did not use symptom-score analysis. This is the first double-blind, histamine placebo-controlled study of grass immunotherapy that demonstrates efficacy by symptom-score index evaluation. IPG is a safe, clinically effective, and potentially cost-effective therapy for grass pollinosis.