[In vitro induction of immune response by dendritic cells pulsed with TRAG-3-derived cytotoxic T lymphocyte epitope]

Abstract

Objective: To explore the in vitro immune response to taxol resistance associated antigen 3 (TRAG-3)-derived cytotoxic T lymphocyte (CTL) epitope-pulsed dendritic cell (DC).

Methods: The HLA-A2.1 restricted CTL epitope of TRAG-3 was previously identified to be a nonameric peptide sequence from 58 to 66 amino acid residues (TRAG-3(58-66)). The peptide was synthesized according to Fmos procedure, purified and molecular weight determined. Peripheral blood mononuclear cells (PBMC) of normal HLA-A2.1(+) individuals were used to isolate DC and DCs' phenotype identified by flow cytometry. Induction of CTL was achieved by in vitro stimulation of HLA-A2.1(+) PBMC with peptide-pulsed DC. CTL activity against HLA-A2.1(+)/TRAG-3(+) melanoma cell line LB373-MEL was assessed by (51)Cr release assay and IFN-gamma released by ELISA.

Results: The synthetic nonameric peptide was above 90% pure and the determined values of molecular weight were conformed to their theoretical values. The phenotype of the isolate DCs was characteristic for mature ones. PBMC stimulated in vitro by TRAG-3-derived epitope-pulsed DCs for three times could specifically kill the target cells and secreted high concentration of IFN-gamma.

Conclusion: TRAG-3-derived epitope-pulsed DC can elicit specific anti-tumor immune response in vitro. Clinical trials using it as tumor vaccine may be feasible as specific immunotherapy for patients with TRAG-3 expressing cancers.