Controlled evaluation of allergoid in the immunotherapy of ragweed hay fever.

Immunotherapy with ragweed allergoid administered in a clustered regimen, placebos in a clustered regimen, and unaltered ragweed extract (allergen) in a weekly regimen were compared in three groups of hay fever patients carefully matched for ragweed sensitivity. The allergoid and placebo comparison was performed double-blind and the unaltered ragweed extract comparison was single-blind. In terms of antigen E (AgE) equivalents, doses were about 50 times higher in the allergoid-treated group than in the allergen-treated group. Whereas there was no immunologic response to placebos, the allergoid regimen produced a more rapid serum IgG antibody response, with significantly higher posttreatment levels than those in the allergen regimen. Initial IgE antibody rises and subsequent slow declines were similar. Symptom-medication scores were similar in the two specifically treated groups and significantly less than scores reported by the placebo group (p less than 0.01). Due to an overestimate of the initial allergoid doses, systemic reactions occurred mostly in the early visits with allergoid treatment, whereas systemic reactions appeared late in the allergen treatment. The overall incidence was similar. In a second year, after 8 mo of no injections, a preseasonal booster regimen with both materials produced virtually no untoward reactions. During the period of no injections, IgG antibody declines were modest and, after boosters, IgG antibody levels rose promptly. Clinical results in both groups were again excellent, with an advantage for allergoid.