T_H2 lymphocytes play an important role in the induction and maintenance phase of type I allergy. Modulation of the responses of T_H2 lymphocytes by novel forms of antigen-presenting platforms may help shape the immune response to allergen and palliate allergic diseases.

To present HLA class II/allergen-peptide complexes on virus-like particles (VLPs) and to evaluate their potential to modulate allergen-specific T-cell responses.

Virus-like particles that express the immunodominant T-cell epitope Art v 1_25-34 of the major mugwort pollen allergen in the context of HLA-DR1 and costimulatory molecules were produced by transfection of 293 cells. The effect of VLPs on IL-2 promoter activity, proliferation, and cytokine production of allergen-specific T cells derived from donors with and without mugwort pollen allergy was determined.

Flow-cytometric analyses showed that HLA class II molecules, invariant chain::Art v 1 fusion proteins, and costimulatory molecules were expressed on 293 cells. Biochemical analyses confirmed that these molecules were efficiently targeted to VLPs. The engineered VLPs activated Art v 1–specific T cells in a costimulation-dependent manner. VLPs lacking costimulators induced T-cell unresponsiveness, which was overcome by addition of exogenous IL-2. Costimulation could be provided by CD80, CD86, or CD58 and induced distinct cytokine profiles in allergen-specific T cells. Unlike the other costimulatory molecules, CD58 induced IL-10/IFN-γ–secreting T cells.

Virus-like particles represent a novel, modular, acellular antigen-presenting system able to modulate the responses of allergen-specific T cells in a costimulator-dependent fashion. Allergen-specific VLPs show promise as tools for specific immunotherapy of allergic diseases.