Allergenicity, immunogenicity, and safety of immunotherapy with various molecular weight ranges of polymerized ragweed

Since the observation had been made that allergenicity of polymerized ragweed (PRW) varies inversely with molecular weight over ranges we had studied previously, we conducted this study to determine the utility of immunotherapy with PRW molecular weight >20,000,000 alone or as part of a final product pool. Twenty-one patients with ragweed pollinosis were randomized into three groups on the basis of ragweed skin test titration. Each patient received 500 μg AgE (50,000 PNU) of one of the following molecular-weight ranges: PRW A > 500,000; PRW B 200,000 to 20,000,000; and PRW C > 20,000,000. There was no difference between PRW A, B, and C by intradermal end point titration, by incidence of large local reactions, by amount of erythema or induration from injections, or by rise in blocking antibody that was significant in each group. There were no systemic reactions nor any changes in clinical laboratory parameters. In summary, each of the molecular-weight ranges of PRW studied was similarly allergenic, immunogenic, and safe to administer, and thus PRW >20,000,000 can be used for immunotherapy as a part of the final product pool. This has the advantages of increasing yields and of simplifying the fractionation by eliminating one chromatographic process.