Abstract: Objective To investigate the kinetic effects of cell-penetrating peptide (CPP) Tat_49-57 on the presentation of human papillomavirus (HPV) 16E7_49-57,a MHC class I-restricted epitope of cytotoxic T lymphocytes (CTL).Methods A fusion protein containing CPP Tat_49-57 and E7_49-57,the unique HLA-A₂/H2-K^b+ restricted CTL epitope of HPV16E7,was synthesized by standard solid-phase Fmoc chemistry.A N-terminal extended epitope and an irrelated peptide were synthesized respectively as controls.A macrophage cell line Ana-1 was cultured and incubated with the antigen peptides for various durations.Fluorescence activated cell sorter (FACS) was employed with FITC-labeled monoclone antibody to E7_49-57/K^b to detect the expression of E7_49-57 on the surface of Ana-1 cells.Results At the early stage (within 80 min) of incubation,Tat-E7_49-57 could be uptaken by APCs and presented by MHC classⅠmolecules much more rapidly than other antigen peptides,but its presentation effiency was relatively lower as compared with E7_49-57 (P>0.05).At the late stage (8-48 h) of incubation,the presence time of E7_49-57/K^b was significantly prolonged on the surface of Tat-E7_49-57-incubated cells than that on the surface of other peptides-incubated cells (all P<0.05).Conclusion CPP can effectively enhance the immunogenicity of exogenous antigen peptides by promoting MHC classⅠantigen presentation of CTL epitopes.

Key words: Papillomavirus,human, Antigen presentation, Cell-penetrating peptides, CTL epitope