Clinical and immunologic evaluation of glutaraldehyde-modified tyrosine-adsorbed short ragweed extract: a double-blind, placebo-controlled trial.

Glutaraldehyde-modified, tyrosine-adsorbed ragweed extract (GTR) is a modification of allergen extract to reduce allergenicity but retain immunogenicity. We evaluated the clinical efficacy and immunologic changes associated with the administration of GTR (16,350 protein nitrogen units) or placebo to a group of 100 atopic subjects with ragweed hay fever. The study was carried out in a double-blind, placebo-controlled fashion. Clinical response was measured by daily symptom diaries. physician evaluations, and patient responses. Changes in ragweed-specific IgE and IgG antibody were evaluated with an amplified enzyme-linked immunosorbent assay (alpha-ELISA) and were compared with measurements by RAST and a protein A-binding assay for IgG antibody. Treatment with GTR resulted in a sixfold increase in blocking IgG antibody and a small increase in IgE-specific antibody. No changes occurred in the placebo treated group. Mild immediate local reactions occurred after 74% of injections, and late-onset local reactions occurred after 62% of injections in the treated group. The placebo-treated group experienced immediate or late local reaction after only 12% of injections. There were two mild late-onset urticarial reactions of a generalized nature in the treatment group. The treatment group experienced significantly fewer symptoms than the placebo group throughout the season (p less than 0.02), although the difference was not dramatic. The results showed that GTR could be safely given in five preseasonal injections, with retained immunogenicity but less potential for generalized reactions. GTR is an improved method of allergy immunotherapy with the potential for clinical benefit when used in a brief preseasonal treatment regimen.