A novel approach to specific allergy treatment: the recombinant allergen-S-layer fusion protein rSbsC-Bet v 1 matures dendritic cells that prime Th0/Th1 and IL-10-producing regulatory T cells.

An ideal vaccine for allergen-specific immunotherapy of type I allergies should display reduced mediator-releasing capacity, induce maturation of APC, and modify the disease-eliciting Th2-dominated allergen-specific response to a more physiological response. We have previously shown that rSbsC-Bet v 1, the recombinant fusion protein of a bacterial surface (S-layer) protein of Geobacillus stearothermophilus ATCC 12980 and the major birch pollen allergen Bet v 1, exhibited reduced allergenicity and induced IFN-gamma and IL-10 synthesis in Bet v 1-specific Th2 clones. In this study, we characterized the effects of rSbsC-Bet v 1 on immature monocyte-derived dendritic cells (mdDC) and the consequences for the polarization of naive CD4(+) T lymphocytes isolated from the blood of birch pollen-allergic patients. mdDC responded to rSbsC-Bet v 1 with a significant up-regulation of costimulatory molecules, functional maturation, and the synthesis of IL-10 and IL-12. mdDC matured with rSbsC-Bet v 1 induced the differentiation of naive T cells into IFN-gamma-producing cells. This effect was IL-12 dependent. In parallel, a substantial number of naive T cells developed into IL-10-producing CD25(+)Foxp3(+)CLTA-4(+) cells capable of active suppression. Thus, rSbsC-Bet v 1 showed immune stimulatory capacity on DC, which then promoted the simultaneous differentiation of Th0/Th1 cells and regulatory T cells. These data further support that the concept of conjugating allergens to bacterial agents is a promising approach to improve vaccines for specific immunotherapy of atopic allergies.