Allergens displayed on Virus-Like Particles are highly immunogenic but fail to activate human mast cells

Abstract

The goal of allergen-specific immunotherapy is the induction of protective immune responses in the absence of anaphylactic reactions. We have previously shown that Fel d 1, the major cat allergen, displayed in a repetitive fashion on virus-like particles (VLPs) may fulfill these criteria. Specifically, Fel d 1 on VLPs induced strongly increased IgG responses compared to the free allergen in mice while anaphylactic reactions were essentially abolished. Here we extend these findings to human mast cells and offer a mechanistic explanation for the reduced anaphylactic activity. By performing allergen binding studies and cellular activation assays, we demonstrate that the inability of Fel d 1 displayed on VLPs to activate mast cells is based on a biophysical as well as a biochemical mechanism. Firstly, Fel d 1 on VLPs showed a strongly impaired ability to bind to surface-bound IgE as assessed by Surface Plasmon Resonance (SPR) as well as flow cytometry. Secondly, despite residual binding, repetitively displayed allergen on VLPs failed to cause mast cell activation.

These findings indicate that repetitively displaying allergens on VLPs increases their immunogenicity while reducing their potential to cause anaphylactic reactions by essentially eliminating IgE-mediated activation of mast cells.

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