Objective: To assess the cytotoxicity of cytotoxic T lymphocytes (CTLs) induced by the dendritic cells phagocytosing HLA-A2+ restricted epitope peptides encapsulated in polylactic acid (PLA) microspheres (PLA-AFP218-226) against cell lines HepG2 and T2-loaded with HLA-A2+ restricted epitope peptides derived from alpha fetoprotein (AFP218-226, LLNQHACAV).
Methods: Mature dendritic cells (DCs) were obtained by inducing the monocytes isolated from peripheral blood cells of HLA-A2+ healthy donors with GM-CSF and IL-4. On day 3 from onset of the culture, PLA- AFP218-226 was added to the culture medium, and on day 6, lipoplysaccharide (LPS) was added to it for inducing the immature DCs to mature. The surface phenotype of the mature DCs was determined with fluorescence activated cell sorting (FACS) assay; the cytotoxicity of CTLs induced by the DCs for 7 days against cell lines HepG2 and T2-loaded with AFP218-226 was determined with MTT method; and the avidity between HLA-A2 and AFP218-226 was determined with T2-peptide binding experiment.
Results: There was high avidity between AFP218-266 and HLA-A2. The DCs phagocytosing PLA-AFP218-226 highly expressed CD83, CD86, CD40, etc., and the CTLs induced by the DCs strongly decomposed the HepG2 and T2-loaded with AFP218-226.
Conclusions: The strong cytotoxicity against HepG2 cell lines can be induced in vitro by DCs phagocytosing PLA-AFPM218-226 micospheres, suggesting that PLA-AFP218-226 microspheres can serve as a new type of CTL epitope vaccine for the prophylaxis and treatment of hepatocellular carcinoma.