Inhibitory effects of apple polyphenol extract (AP) and procyanidin contained in AP on in vitro pancreatic lipase activity and in vivo triglyceride absorption in mice and humans were examined. AP and procyanidin considerably inhibited in vitro pancreatic lipase activity. However, polyphenols, except for procyanidin, in AP (i.e., catechins, chalcones, and phenol carboxylic acids) showed weak inhibitory activities on pancreatic lipase. Procyanidins separated by normal-phase chromatography according to the degree of polymerization were also examined. Inhibitory effects of procyanidins increased according to the degree of polymerization from dimer to pentamer. On the other hand, pentamer or greater procyanidins showed maximal inhibitory effects on pancreatic lipase. These results suggested that with respect to in vitro pancreatic lipase inhibition, the degree of polymerization was an important factor and oligomeric procyanidin mainly contributed. Next, we performed a triglyceride tolerance test in mice and humans. Simultaneous ingestion of AP and triglyceride significantly inhibited an increase of plasma triglyceride levels in both models. These results suggested that the oligomeric procyanidins contained in AP inhibited triglyceride absorption by inhibiting pancreatic lipase activity in mice and humans.

A major problem with allergen-specific immunotherapy involving repeated injection of allergens is the risk of an anaphylactic reaction. We engineered the major house dust mite allergen, Der f 2, to reduce its capacity to induce skin test reactivity and histamine release from peripheral blood basophils in allergic patients. The engineered allergen, in which the disulfide bond that linked the N- and C-terminal sequences of Der f 2 was disrupted, retained T-cell epitopes essential for immunotherapy and ability to stimulate T-cell proliferation. Such engineered allergens are potentially useful for safer and more effective immunotherapy for allergies.

Background: Monkeys are considered to have an immune system very similar to that of humans, as compared with mice, rats, and guinea pigs. Although primate allergic models to several pollen allergens have been developed, no model of house dust mite allergy has been reported. In this study, we attempted to induce type I allergy to mite allergens in rhesus monkeys. Methods: Six rhesus monkeys were immunized subcutaneously with crude mite extract adsorbed on aluminum hydroxide for 4 months. Then 5 monkeys positive for IgE production to mite extract were further immunized subcutaneously and conjunctivally with recombinant Der f 2 (rDer f 2). The status of sensitization to mite extract and rDer f 2 in monkeys was examined before and after the immunization. Plasma antigen-specific IgE and IgG levels, cutaneous reaction, and histamine release from peripheral blood leukocytes were measured. After conjunctival immunization, immediate conjunctivitis and leukocyte influx into conjunctiva after rDer f 2 challenge were examined. Results: After immunization with crude mite extract, 5 of 6 sensitized monkeys showed IgE response to the mite, and 4 out of 5 rDer f 2-sensitized monkeys exhibited IgE production to rDer f 2. Three monkeys sensitized with rDer f 2 showed immediate conjunctivitis and conjunctival eosinophilia after applying rDer f 2 to their eyes. Sensitized animals also showed IgG response to mite antigens. Conclusion: Four rhesus monkeys were positive for IgE production and allergic reactions to both mite extract and rDer f 2. These monkeys could represent a useful model for studying the development and regulation of house dust mite allergy.

SUMMARYC8/119S is a mutant of recombinant Der f 2 (rDer f 2), and lacks a disulphide bond possessed by wildtype rDer f 2. In humans and mice, C8/119S has a very weak IgE-binding capacity compared with the wild-type, but possesses a T cell reactivity comparable to that of the wild-type. C8/119S may thus be a safe immunotherapeutic agent for house dust mite allergy. The aim of the present study was to evaluate whether the intranasal administration of C8/119S could suppress an immediate allergic reaction in mice sensitized with wild-type rDer f 2, possessing an allergic activity comparable to native counterparts purified from mite extract. Seven-week-old male A/J mice were immunized with wild-type rDer f 2 four times, and then intranasally administered 0·2-2 mg of wild-type, 0·2-20 mg of C8/119S, or PBS alone, three times a week for 4 weeks. Seven days after the last administration, the mice were examined for an immediate allergic reaction. The animals administered 2 mg of C8/119S (C2.0 group) showed significantly reduced immediate bronchoconstriction provoked by the i.v. injection of 1 and 10 mg of wild-type rDer f 2, compared with the PBS-treated mice. Similar results were obtained when we examined mice 10 weeks after the last administration. The reactions in the other groups given wild-type or C8/119S also tended to decrease in severity in comparison with the animals of the PBS group. The allergic phenotypes of the T cells, B cells, and basophils in the C2.0 group were shifted to that of naive mice without immunization. We conclude that C8/119S has hyposensitizing activities in mice sensitized with wild-type rDer f 2. C8/119S may be useful for immunotherapy of house dust mite allergy.