Passive immunization with allergen-specific IgG antibodies for treatment and prevention of allergy.

IgE antibody-mediated allergies affect more than 25% of the population worldwide. To investigate therapeutic and preventive effects of passive immunization with allergen-specific IgG antibodies on allergy in mouse models we used clinically relevant pollen allergens. In a treatment model, mice were sensitized to the major birch pollen allergen Bet v 1 and to the major grass pollen allergens, Phl p 1 and Phl p 5 and then received passive immunization with rabbit IgG antibodies specific for the sensitizing or an unrelated allergen. In a prevention model, mice obtained passive immunization with allergen-specific rabbit IgG before sensitization. Kinetics of the levels of administered IgG antibodies, effects of administered allergen-specific IgG on allergen-specific IgE reactivity, the development of IgE and IgG responses and on immediate allergic reactions were studied by ELISA, rat basophil leukaemia degranulation assays and skin testing, respectively. Treated mice showed an approximately 80% reduction of allergen-specific IgE binding and basophil degranulation which was associated with the levels of administered allergen-specific IgG antibodies. Preventive administration of allergen-specific IgG antibodies suppressed the development of allergen-specific IgE and IgG1 antibody responses as well as allergen-induced basophil degranulation and skin reactivity. Our results show that passive immunization with allergen-specific IgG antibodies is effective for treatment and prevention of allergy to clinically important pollen allergens in a mouse model and thus may pave the road for the clinical application of allergen-specific antibodies in humans.

Distinctive anti-allergy properties of two probiotic bacterial strains in a mouse model of allergic poly-sensitization.

We compared the immunomodulatory properties of Bifidobacterium longum NCC 3001 and Lactobacillus paracasei NCC 2461 in a mouse model of poly-sensitization to birch and grass pollen allergens. Mucosal application of both strains at the time of sensitization and challenge led to significant suppression of airway inflammation and down-regulated allergen-specific immune responses. In contrast, in the mice treated with probiotics prior to sensitization and challenge, only B. longum displayed protective effects. Our findings stress that the choice of probiotic strain and the timing of the application are crucial for tolerance induction. Furthermore, this is the first demonstration of anti-allergic effects of probiotic bacteria in poly-sensitized mice.