Immunotherapy for cure and prophylaxis of allergic rhinitis

Summary The possible cure of Japanese cedar pollen‐induced allergic rhinitis (AR) by immunotherapy was investigated. The mechanism of cure was also studied from the viewpoint of the T cell response to allergen; it was documented that absence of IL‐5 production from allergen‐stimulated T cells was the major mechanism. The prophylactic aspect of immunotherapy was also investigated. Eighty‐eight asymptomatic subjects who were already sensitized to pollen were recruited. Of these subjects, 31 (prophylactic immunotherapy group) were treated with pollen immunotherapy for 3 years. The remaining 57 individuals (control group) were not treated with pollen immunotherapy. At the end of the 3‐year trial, only 28 of 57 individuals (49.1%) in the control group remained asymptomatic. On the other hand, 27 of 31 individuals (87.1%) in the prophylactic immunotherapy group remained asymptomatic. Prophylactic immunotherapy decreased IL‐4 synthesis from pollen allergen‐stimulated T cells, suggesting that this was the mechanism of prevention of symptoms' outbreak. We next examined whether mite immunotherapy for patients monosensitized to mite allergen could prevent new sensitization to pollens. A total of 132 patients monosensitized to house dust mites were included. Of these individuals, 52 (pharmacotherapy group) were treated with antihistamine tablets for 4 years, and the remaining 80 patients (mite immunotherapy group) were treated with mite immunotherapy for the same time period. Whereas 15 of 52 patients (28.8%) in the pharmacotherapy group attained new sensitization to some kinds of pollen allergens, only five of 80 patients (6.3%) in the mite immunotherapy group attained new sensitization. Our data suggest that mite immunotherapy can prevent new sensitization to pollen allergens. It is therefore concluded that pollen immunotherapy cannot only cure pollen‐induced AR but also prevent outbreaks of pollen‐induced AR, and that mite immunotherapy can prevent new sensitization to pollen allergens.