PRESERVED EPITOPE-SPECIFIC T-CELL ACTIVATION BY RECOMBINANT BET-V-1-MBP FUSION PROTEINS

Background. Allergen-specific T cells play an important role in the al lergic immune response, and are thought to be the principal target in specific immunotherapy. Objective. The aim of the present study was to evaluate if fusion proteins of allergens with bacterial proteins can be used to activate and bias allergen-specific T cells, and to charact erize T cell epitopes. Methods. The complete gene of Bet v 1, the majo r birch pollen allergen, was amplified by PCR from birch pollen mRNA, and cloned in pKK223-3. The complete gene or truncated sequences were transferred to pMAL-c and expressed in E. coli as fusion proteins with maltose binding protein (MBP). The complete fusion protein, and the t runcated fusion proteins were used for studies with Bet v 1-specific T cells. Results. Bet v 1-specific T cells reacted similarly with purif ied and crude Bet v I-MBP proteins. Therefore, crude preparations were used to study the epitope-specificity of 11 Bet v 1-specific T cell c lones. Six distinct T cell epitopes were determined in this way. Inter estingly, the T cell epitope of three T cell clones, that did not reac t with synthetic peptides in a previous study, was identified. In addi tion, the presence of MBP as a fusion partner to Bet v 1 was shown to influence TH2/TH1 cytokine production in T cell lines, but not in esta blished T cell clones. Conclusion. Using crude preparations of recombi nant fusion proteins of Bet v 1 with MBP, multiple T cell epitopes wer e identified in Bet v 1. As T cell activation is preserved in this sys tem, the generation of recombinant allergens with TH1-inducing protein s as fusion partners might be considered as a T-cell targeted approach for specific immunotherapy.