Subcutaneous immunotherapy with purified Der p1 and 2 suppresses type 2 immunity in a murine asthma model.

BACKGROUND: Allergen-specific immunotherapy can induce long-term suppression of allergic symptoms, reduce medication use, and prevent exacerbations of allergic rhinitis and asthma. Current treatment is based on crude allergen extracts, which contain immunostimulatory components such as ß-glucans, chitins, and endotoxin. Use of purified or recombinant allergens might therefore increase efficacy of treatment. AIMS: Here, we test application of purified natural group 1 and 2 allergens from Dermatophagoides pteronyssinus (Der p) for subcutaneous immunotherapy (SCIT) treatment in a house dust mite (HDM)-driven mouse model of allergic asthma. MATERIALS AND METHODS: HDM-sensitized mice received SCIT with crude HDM extract, a mixture of purified Der p1 and 2 (DerP1/2), or placebo. Upon challenges, we measured specific immunoglobulin responses, allergen-induced ear swelling response (ESR), airway hyperresponsiveness (AHR), and inflammation in bronchoalveolar lavage fluid (BAL) and lung tissue. RESULTS: ESR measurement shows suppression of early allergic response in HDM-SCIT- and DerP1/2-SCIT-treated mice. Both HDM-SCIT and DerP1/2-SCIT are able to suppress AHR and eosinophilic inflammation. In contrast, only DerP1/2-SCIT is able to significantly suppress type 2 cytokines in lung tissue and BAL fluid. Moreover, DerP1/2-SCIT treatment is uniquely able suppress CCL20 and showed a trend toward suppression of IL-33, CCL17 and eotaxin levels in lung tissue. DISCUSSION: Taken together, these data show that purified DerP1/2-SCIT is able to not only suppress AHR and inflammation, but also has superior activity toward suppression of Th2 cells and HDM-induced activation of lung structural cells including airway epithelium. CONCLUSIONS: We postulate that treatment with purified natural major allergens derived from HDM will likely increase clinical efficacy of SCIT.

Optimization of skin testing. I. Choosing allergen concentrations and cutoff values by factorial design.

Standardized extracts of Phleum pratensis (grass) and Dermatophagoides pteronyssinus (house-dust mite) were used as test allergens for multiple regression in order to determine optimum concentrations and cutoff values with regard to diagnostic capacity and safety. If a RAST value of class 1 or more was taken as an indication of sensitization, it was found that the optimum concentrations for the detection of sensitization are in the range 10-100 BU/ml and 1500-10,000 BU/ml for intracutaneous tests (ICT) and skin prick tests (SPT), respectively. The skin test results were expressed as histamine ratios. Using allergen concentrations of 30 and 3,000 BU/ml, we found cutoff values of 0.87 and 0.53 and predictive values of 87.1% and 79.1% for ICT and SPT, respectively. The maximum wheal size (mean wheal size + 2 SD) to be expected in 95% of the population was 26.6 mm (ICT) and 10.9 mm (SPT), sizes regarded as safe by most clinicians. In conclusion, by using this method with a limited number of patients, one can probably improve the diagnostic precision and safety of the skin test. In the second part of this study, these hypotheses were prospectively tested in a multicenter study.