ALLERGIC RHINITIS TO RAGWEED POLLEN .1. REASSESSMENT OF THE EFFECTS OF IMMUNOTHERAPY ON CELLULAR AND HUMORAL RESPONSES

This work presents a double-blind, placebo-controlled study of 27 patients with allergic rhinitis to ragweed who received preseasonal desensitization immunotherapy [IT] with alum-precipitated aqueous ragweed extracts. We reassessed the following parameters in relation to clinical responses: clinical scores, nasal reactivity to a provocative dose of ragweed causing a 75% fall in airflow rate (PD75), ragweed IgE and IgG, and ragweed-induced basophil histamine release (BHR). First, the nasal PD75 correlated with the severity of nasal symptoms (p < 0.05). Second, we confirmed a significant symptomatic improvement in the IT-treated group either by clinical scores (p < 0.05) or the prevention of the seasonal fall of the PD75 (p < 0.005). Also, IT reduced the seasonal rise of IgE (p < 0.02) and induced an increase in IgG (p < 0.01) and a decrease in BHR (p < 0.03). There was a significant correlation between IgE and BHR (r = 0.80; p < 0.01). After selecting out the effects of IgE, the BHR was still higher in the placebo-treated group than in the IT-treated group (p < 0.02), suggesting the involvement of other modulating factors. Symptomatic improvement after IT correlated only with the summation of both IgE and BHR (PD75; r = 0.64; p < 0.005). This observation suggests that the severity of clinical symptoms is determined by several interacting factors and not by the antibody response alone.