1. [Identification of a novel HLA-A2-restrictive CTL epitope of an ovary cancer-associated antigen OVA66]
Shu Jin, Ying Wang, Shu-jun Wang, Hui-zhen Zhang, Mei-xing Li, Ying Chen, Hai-liang Ge Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi. 2005 Mar;21(2):233-6, 242.
Aim: To identify a novel HLA-A2-restrictive CTL epitope of an ovary cancer-associated antigen OVA66. Methods: Dendritic cells (DCs), induced from peripheral blood mononuclear cells(PBMCs) by cytokines, were confirmed by morphological observation and FACS. Mature DCs were pulsed with each of the two synthesized peptides which were selected as possible CTL epitopes by software analysis. The pulsed DCs were used to stimulate autologous CD8+ T cells from an HLA-A2+ healthy donor. One week later, the peptides-pulsed autologous PBMCs were used to stimulate the CD8+ T cells for another 3 times at weekly intervals. The stimulated CD8+ T cells were used as CTLs. The cytotoxicity of CTLs to target cells was detected by lactate dehydrogenase (LDH) release assay and the number of T cells secreting antigen-specific IFN-gamma in CTLs was analyzed by enzyme-linked immunospot assay (ELISPOT). Results: The results of morphology observation and FACS indicated that mature DCs were induced from PBMCs. Of the two peptides, peptide L235(FLPDHINIV) induced peptide-specific CD8+ T cells that lysed HLA-A2+ T2 cells pulsed with L235 and OVA66+/HLA-A2+ SW480 cells. Compared with control peptide, L235 increased the number of IFN-gamma producing T cells. Conclusion: This novel OVA66-derived CTL epitope L235 can induce HLA-A2-restrictive CTL response, which lays the foundation for preparation of tumor-specific peptide vaccine.
2. High frequencies of circulating melanoma-reactive CD8+ T cells in patients with advanced melanoma
A Letsch, U Keilholz, D Schadendorf, D Nagorsen, A Schmittel, E Thiel, C Scheibenbogen Int J Cancer. 2000 Sep 1;87(5):659-64.
To determine whether circulating tumor-reactive T cells are present in melanoma patients, unstimulated T cells from peripheral blood were tested for recognition of HLA-A2- or HLA-A1-matched melanoma cell lines using the ELISPOT assay. Eleven out of 19 patients with metastatic melanoma had a T-cell response with up to 0.81%, 0.78%, 0. 53%, 0.12%, 0.10%, 0.09%, 0.07%, 0.06%, 0.06%, 0.04%, and 0.04% of peripheral blood mononuclear cells (PBMC) secreting IFNgamma upon exposure to various HLA-A2- or HLA-A1-matched melanoma cell lines. These T-cell responses were mediated by CD8+ T cells and could specifically be blocked by an anti-HLA-A2 antibody in HLA-A2-positive patients. Separation experiments performed in one melanoma patient showed tumor-reactive T cells in both the CD8+ effector T cell (CD45RA+/IFNgamma+) as well as the CD8+ memory T-cell compartment (CD45RO+/IFNgamma+). In 3 out of 5 patients, in whom autologous cell lines were available, similar frequencies of T cells in response to HLA-A1- or HLA-A2-matched allogeneic and autologous tumor cells were observed, while 2 patients had a T-cell response restricted to either the autologous or the allogeneic cell lines. These results give evidence for the presence of tumor-reactive CD8+ T cells in more than half of melanoma patients tested. Although some of these patients have clinical evidence for an immunological-mediated tumor control, several patients have growing tumors suggesting presence of escape mechanisms.
3. DCs pulsed with novel HLA-A2-restricted CTL epitopes against hepatitis C virus induced a broadly reactive anti-HCV-specific T lymphocyte response
Zhongsheng Guo, Henghui Zhang, Huiying Rao, Dong Jiang, Xu Cong, Bo Feng, Jianghua Wang, Lai Wei, Hongsong Chen PLoS One. 2012;7(6):e38390. doi: 10.1371/journal.pone.0038390. Epub 2012 Jun 12.
Objective: To determine the capacity of dendritic cells (DCs) loaded with single or multiple-peptide mixtures of novel hepatitis C virus (HCV) epitopes to stimulate HCV-specific cytotoxic T lymphocyte (CTL) effector functions. Methods: A bioinformatics approach was used to predict HLA-A2-restricted HCV-specific CTL epitopes, and the predicted peptides identified from this screen were synthesized. Subsequent IFN-γ ELISPOT analysis detected the stimulating function of these peptides in peripheral blood mononuclear cells (PBMCs) from both chronic and self-limited HCV infected subjects (subjects exhibiting spontaneous HCV clearance). Mature DCs, derived in vitro from CD14(+) monocytes harvested from the study subjects by incubation with appropriate cytokine cocktails, were loaded with novel peptide or epitope peptide mixtures and co-cultured with autologous T lymphocytes. Granzyme B (GrB) and IFN-γ ELISPOT analysis was used to test for epitope-specific CTL responses. T-cell-derived cytokines contained in the co-cultured supernatant were detected by flow cytometry. Results: We identified 7 novel HLA-A2-restricted HCV-specific CTL epitopes that increased the frequency of IFN-γ-producing T cells compared to other epitopes, as assayed by measuring spot forming cells (SFCs). Two epitopes had the strongest stimulating capability in the self-limited subjects, one found in the E2 and one in the NS2 region of HCV; five epitopes had a strong stimulating capacity in both chronic and self-limited HCV infection, but were stronger in the self-limited subjects. They were distributed in E2, NS2, NS3, NS4, and NS5 regions of HCV, respectively. We also found that mDCs loaded with novel peptide mixtures could significantly increase GrB and IFN-γ SFCs as compared to single peptides, especially in chronic HCV infection subjects. Additionally, we found that DCs pulsed with multiple epitope peptide mixtures induced a Th1-biased immune response. Conclusions: Seven novel and strongly stimulating HLA-A2-restricted HCV-specific CTL epitopes were identified. Furthermore, DCs loaded with multiple-epitope peptide mixtures induced epitope-specific CTLs responses.
