Identification of novel Lck‐derived T helper epitope long peptides applicable for HLA‐A2⁺ cancer patients as cancer vaccine

Abstract

The present study attempted to identify T helper epitope long peptides capable of inducing cytotoxic T lymphocytes (CTL) from Lck antigen (p56Lck), the src family tyrosine kinase, which is known to be aberrantly expressed in metastatic cancers cells, in order to develop a long peptide‐based cancer vaccine for HLA‐A2+ cancer patients. Based on the biding motif to the HLA‐DR and HLA‐A2 alleles, 94 peptides were prepared from the Lck antigen. These peptides were screened for their reactivity to immunoglobulin G (IgG) from plasma of cancer patients, followed by testing of their ability to induce both CD4+ and CD8+ T lymphocytes showing not only peptide‐specific IFN‐γ production but cytotoxicity against HLA‐A2+ cancer cells from peripheral blood mononuclear cells (PBMC) of HLA‐A2+ cancer patients. Among 94 peptides tested, the three T helper epitope long peptides and their inner CTL epitope short peptides with HLA‐A2 binding motifs were frequently recognized by IgG of cancer patients, and efficiently induced both CD4+ IFN‐γ+ and CD8+ IFN‐γ+ T lymphocytes. Patients' PBMC stimulated with these long peptides showed cytotoxicity against HLA‐A2+ Lck+ cancer cells in HLA‐class I and HLA‐class II dependent manners. These three peptides might be useful for long peptide‐based vaccines for HLA‐A2+cancer patients with Lck+ tumor cells.

Antitumor activity of antibody against cytotoxic T lymphocyte epitope peptide of lymphocyte‐specific protein tyrosine kinase

“…The presence of humoral responses to certain CTL epitope peptides has been reported over the past decade, and vaccination of these peptides for cancer patients often induced increased peptide‐specific IgG responses . However, to our knowledge, there are no published reports on the biological activity of antibodies against CTL epitope peptides.…”

“…For the competition assay, 10 000‐fold diluted antibody was incubated with 100 μL peptide‐coupled color‐coded beads and 5 μL each of the corresponding peptides (10 μg/mL) for 1.5 hours at 30°C. The binding of anti‐peptide IgG was detected by the same method as that described above . For purification, the cloned cells were cultured with hybridoma serum‐free medium (Life Technologies, Carlsbad, CA, USA).…”

“…We previously reported that the IgG against CTL epitope peptides from Lck antigen have been observed in the majority of healthy donors and cancer patients in correlation with the overall survival of cancer patients . We also reported that an increase in the IgG responses to the vaccinated peptides were favorable for the overall survival of cancer patients under PPV, in which four of 31 warehouse peptides were selected by pre‐existing peptide‐specific IgG levels .…”

“…8 Immunoglobulin G reactive to Lck peptide at positions 486-494 (Lck-486) was found to be expressed in some metastatic tumor cells and T cells at the tumor site, but not expressed in tumor cells from non-metastatic primary tumor cells. [1][2][3] In the present study, we investigated the biological activity of a mAb reacting to the Lck peptide at positions 486-494 (anti-Lck-486 mAb), and showed it had antitumor activity.…”

Follistatin‐like protein 1 contributes to dendritic cell and T‐lymphocyte activation in nasopharyngeal carcinoma patients by altering nuclear factor κb and Jun N‐terminal kinase expression

“…Our results, on the basis of ELISpot assays, RT‐PCR and flow cytometry (Figures and ), show the effects of FSTL1 on antigen‐antibody recognition and IFN‐γ production. INF‐γ inhibits proliferation in malignant cells, regulates the body's immune response and activates CD8+ T lymphocytes to destroy circulating tumor cells . The tetramer detection method uses a single MHC‐peptide tetramer molecule to reveal TCR expression on the surface of cytotoxic T lymphocytes, resulting in their rapid detection by flow cytometry .…”