Effects of immunotherapy with a purified standardized allergen preparation of Dermatophagoides farinae in adults with perennial allergic rhinoconjunctivitis

Immunotherapy (IT) was performed for 12 months with a purified and standardized preparation of Dermatophagoides farinae. Twenty adults with rhinoconjunctivitis sensitive to house-dust mite were given IT, and a similar group of 11 patients served as open controls. A total of 512 injections were given. Twenty-eight episodes of allergic side-effects occurred, 13 general and 15 local, most of them during the initial incremental dose period. No severe reactions started later than 30 min after the injection. One patient suffered anaphylactic shock. In this patient, specific antibodies fell immediately, followed by an increase within 1 week. The therapy group improved significantly in relation to the open controls in patients' subjective evaluation of symptoms ( P <0.028) and skin ( P <0.0001) and conjunctival ( P <0.001) sensitivity. Specific IgE increased in controls ( P <0.0001) but not in IT-treated patients during the "mite season;" that is, there was a significant difference in change during the observation period ( P <0.0001). There was also a difference in change of specific IgG between the groups during the first 4–5 months and the whole year ( P <0.0001), but not from 4–5 months to 12 months. In contrast to changes in antibody titers (IgG, P =0.04), changes in conjunctival ( P <0.01) and especially skin sensitivity ( P <0.005) correlated well with subjective improvement. This implies that the skin prick test and the conjunctival test can be recommended for follow-up of IT. Furthermore, we recommend that changes in skin sensitivity be expressed as change in allergen concentration either inducing the same wheal response before and after IT as evaluated by parallel-line bioassay, or inducing the same wheal response before and after IT as that induced by histamine tested at the same time. Finally, our findings support the hypothesis of a switch from IgE + to IgE - during successful IT.