HLA-A*0201-restricted CTL epitope of a novel osteosarcoma antigen, papillomavirus binding factor.

Abstract

BACKGROUND:

To develop peptide-based immunotherapy for osteosarcoma, we previously identified papillomavirus binding factor (PBF) as a CTL-defined osteosarcoma antigen in the context of HLA-B55. However, clinical application of PBF-based immunotherapy requires identification of naturally presented CTL epitopes in osteosarcoma cells in the context of more common HLA molecules such as HLA-A2.

METHODS:

Ten peptides with the HLA-A*0201 binding motif were synthesized from the amino acid sequence of PBF according to the BIMAS score and screened with an HLA class I stabilization assay. The frequency of CTLs recognizing the selected PBF-derived peptide was determined in peripheral blood of five HLA-A*0201+ patients with osteosarcoma using limiting dilution (LD)/mixed lymphocyte peptide culture (MLPC) followed by tetramer-based frequency analysis. Attempts were made to establish PBF-specific CTL clones from the tetramer-positive CTL pool by a combination of limiting dilution and single-cell sorting. The cytotoxicity of CTLs was assessed by 51Cr release assay.

RESULTS:

Peptide PBF A2.2 showed the highest affinity to HLA-A*0201. CD8+ T cells reacting with the PBF A2.2 peptide were detected in three of five patients at frequencies from 2 x 10-7 to 5 x 10-6. A tetramer-positive PBF A2.2-specific CTL line, 5A9, specifically lysed allogeneic osteosarcoma cell lines that expressed both PBF and either HLA-A*0201 or HLA-A*0206, autologous tumor cells, and T2 pulsed with PBF A2.2. Five of 12 tetramer-positive CTL clones also lysed allogeneic osteosarcoma cell lines expressing both PBF and either HLA-A*0201 or HLA-A*0206 and T2 pulsed with PBF A2.2.

CONCLUSION:

These findings indicate that PBF A2.2 serves as a CTL epitope on osteosarcoma cells in the context of HLA-A*0201, and potentially, HLA-A*0206. This extends the availability of PBF-derived therapeutic peptide vaccines for patients with osteosarcoma.

• Authors: Tomohide Tsukahara, Satoshi Kawaguchi, Toshihiko Torigoe, Akari Takahashi, Masaki Murase, Masanobu Kano, Takuro Wada, Mitsunori Kaya, Satoshi Nagoya, Toshihiko Yamashita, Noriyuki Sato
• Journal: Journal of translational medicine (J Transl Med) Vol. 7 Pg. 44 (Jun 12 2009) ISSN: 1479-5876 [Electronic] England
• PMID: 19523231 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antigens, Neoplasm
• Epitopes
• HLA-A Antigens
• HLA-A*02:01 antigen
• HLA-A2 Antigen

Topics

• Antigens, Neoplasm (immunology, metabolism)
• Case-Control Studies
• Cell Line, Tumor
• Epitopes (immunology)
• Genotype
• HLA-A Antigens (biosynthesis, immunology)
• HLA-A2 Antigen
• Humans
• Immunotherapy (methods)
• K562 Cells
• Lymphocyte Culture Test, Mixed
• Osteosarcoma (immunology)
• Protein Binding
• T-Lymphocytes, Cytotoxic (immunology)