Prolonged antigen-exposure with carbohydrate particle based vaccination prevents allergic immune responses in sensitized mice

Background:  Defined particles carrying tightly bound allergens at high density have been suggested as alternatives in allergy vaccination. Carbohydrate based particles (CBP), sized 2 μm, provide a platform for covalent coupling of allergens.
Objective:  To investigate the mechanisms of antigen presentation by CBP, as well as cellular and humoral responses after vaccination with the major cat allergen Fel d 1, covalently coupled to CBP.
Methods:  Mice ( n  = 10/group) were subcutaneously vaccinated with CBP-rFel d 1, CBP or phosphate buffer saline (PBS) before sensitization with rFel d 1 and challenged with cat dander extract. Fluorescent and ⁷⁵Se-radiolabeled tracking of allergens and particles were performed with flow cytometry and whole-body autoradiography. Humoral, cellular and regulatory immune responses were analyzed by ELISA and flow cytometry. Cytokines were measured in bronchoalveolar lavage fluid and splenocyte cultures.
Results:  CBP-rFel d 1 prevented induction of airway inflammation and induced allergen-specific T-cell anergy. CBP-rFel d 1 also induced rapid IgM and IgG1-responses compared with soluble rFel d 1. Particles were phagocytosed by antigen-presenting cells and transported to draining lymph nodes and spleen. Moreover, antigen coupled to CBP remained longer at the injection site compared with alum.
Conclusions:  Covalent coupling of rFel d 1 to CBP induces rapid antibody production, prevents induction of allergic immune responses and systemic allergen spreading. Thus, CBP comprise several attractive adjuvant features for use in allergy vaccination.
Clinical Implications:  Prolonged allergen exposure through covalent coupling to particles suitable for phagocytosis, provides an adjuvant for safer and efficient allergy vaccination.