Proteolytic activity of Per a 10 modulates DCs towards type 2 by CD86 up-regulation, high IL-6 and reduced IL-12 secretions. Proteolytically inactive Per a 10 can be further explored for immunotherapy.

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bCockroach allergen is a major risk factor for IgE-mediated allergic response and asthma in sensitized individuals. Serine proteases have been identified from various sources and characterized as major allergens. The present study was aimed to express and characterize recombinant allergen Per a 10 (rPer a 10) from Periplaneta americana. rPer a 10 was expressed in Escherichia coli and purified in soluble form, yielding 0.75 mg/liter of culture. Homology of the Per a 10 protein sequence exhibited 27 to 38% similarity to the mite serine protease and 41 to 52% similarity to other insect trypsins. The purified rPer a 10 protein resolved at 28 kDa on SDS-PAGE and was recognized by cockroach-hypersensitive patients' sera by immunoblotting and enzymelinked immunosorbent assay (ELISA). In competitive ELISA, rPer a 10 required 96 ng of purified protein for 50% inhibition of IgE binding, whereas 34 ng of native protein (nPer a 10) was required for the same inhibition. rPer a 10 and nPer a 10 induced basophil histamine release in the range of 47 to 64% and 60 to 85%, respectively, when sensitized with cockroach-hypersensitive patients' sera. In conclusion, Per a 10 was subcloned, and the protein was purified to homogeneity. rPer a 10 showed reduced IgE binding and histamine release and showed no proteolytic activity. These data suggest that rPer a 10 has potential for immunotherapy.

IntroductionThere is a need to evaluate the safety and efficacy of intralymphatic immunotherapy (ILIT) for inducing tolerance in patients with allergic rhinitis.MethodsThirty‐seven patients with seasonal allergic symptoms to birch and grass pollen and skin prick test >3 mm and/or IgE to birch and timothy >0.35 kU/L were randomized to either ILIT, with three doses of 0.1 mL of birch pollen and 5‐grass pollen allergen extracts on aluminium hydroxide (10,000 SQ‐U/ml; ALK‐Abelló) or placebo using ultrasound‐guided intralymphatic injections at monthly intervals. Daily combined symptom medical score and rhinoconjunctivitis total symptom score were recorded during the peak pollen seasons the year before and after treatment. Rhinoconjunctivitis total symptom score, medication score and rhinoconjunctivitis quality of life questionnaire were recorded annually starting 2 years after treatment. Circulating proportions of T helper cell subsets and allergen‐induced cytokine and chemokine production were analysed using flow cytometry and ELISA.ResultsThere were no differences between the groups related to daily combined symptom medical score the year before and after treatment. Two years after ILIT (after unblinding), the actively treated group reported significantly fewer symptoms, lower medication use and improved quality of life than did the placebo group. After the pollen seasons the year after ILIT, T regulatory cell frequencies and grass‐induced IFN‐γ levels increased only in the actively treated group.ConclusionIn this randomized controlled trial, ILIT with birch and grass pollen extract was safe and accompanied by immunological changes. Further studies are required to confirm or refute the efficacy of the treatment.

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