Double-blind, placebo-controlled immunotherapy with a high-molecular-weight, formalinized allergoid in grass pollen allergy.

Specific immunotherapy is effective in grass pollen allergy with standardized extracts and formalinized allergoids; but systemic reactions are not uncommon. A high-molecular-weight (greater than 85,000 daltons), formalinized allergoid was investigated in a double-blind, placebo-controlled study to assess its safety and efficacy. Twenty patients received a placebo and 39 the allergoid using a rather aggressive protocol. Five patients developed a mild and transient systemic reaction with high doses of allergoid and one had a more severe reaction requiring treatment. Nasal challenges performed with orchard grass pollen grains showed that the threshold number of grains eliciting nasal symptoms was significantly (p less than 0.01) greater in the treated group. This group had significantly (p less than 0.01) less nasal symptoms during the season and specific IgG levels were significantly (p less than 0.01) elevated. There was a significant (p less than 0.01) correlation between nasal challenges and nasal symptoms during the season but no correlation between IgG and symptoms. There was no dose-dependent effect of allergoids.