Polymerized whole ragweed: Human safety and immune response

Polymerized ragweed (PRW) has been shown to have reduced allergenicity while maintaining immunogenicity. In order to evaluate whether the reduced allergenicity would permit high initial doses and rapid progression to maintenance, two groups of subjects with ragweed pollenosis were placed on immunotherapy with PRW standardized for antigen E (AgE) content. Group I, 28 subjects, received an initial dose of 100 protein nitrogen units (PNU) (1 μg AgE) and reached a maintenance dose of 1,000 PNU (10 μg AgE) in four weekly injections. In the first 10 wk each subject received 7,850 PNU (78.5 μg AgE). Group II, six subjects, received an initial dose of 100 PNU (1 μg AgE) and after 11 weekly injections received 30,000 PNU (300 μg AgE). No anaphylactic reactions occurred in the study groups. In group I, three large immediate-type local reactions and nine large late-type reactions occurred in 110 injections. Anti-AgE antibody activity in group I rose from a pretreatment mean value of 264 ng AgE bound per milliliter serum to a posttreatment value of 3,182. The major rise occurred after only 4 wk of therapy. In group II, anti-AgE antibody activity rose from 66 to 2,123 after the 11 wk of therapy. IgE antibody to AgE did not change to any extent in either group, and histamine release in response to AgE measured in group II patients did not change. Symptom score evaluation of group I patients revealed a marked decrease in symptoms after therapy with PRW. Immunotherapy with PRW can be initiated at higher doses, with rapid attainment of maintenance dosage with safety resulting in a brisk immune response and symptomatic improvement.