Page 198 - 2021_03-Haematologica-web

R. Li et al.
AB
CD
Figure5.Dickkopf-1(DKK1) -longpeptide(LP)inducesDKK1-specifichumanTcellsinvitro.Freshperipheralbloodmononuclearcells(PBMC)derivedfromhealthy 3-76
donors (HLA-A0201 or HLA-DR*4 ) were stimulated with DKK1 -LP plus IL-2 and IL-7 weekly in vitro. (A) Frequency of DKK1-specific CD4 and CD8 3-76
stimulation with DKK1
-LP for 1 week were re-stimulated
with DKK1
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++ ++
IFN-g-secreting cells detected by intracellular staining assay. (B) Percentages of HLA-A*0201-DKK1-P20 tetramer+CD8+ T cells in culture after second or third in vitro
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reduced the percentages of IFN-g-secreting CD4+ T cells. (D) HLA-A*0201-restriction of DKK1
+
-LP-specific CD4 T-cell response. PBMC stimulated with DKK1
-LP. (C) MHC class II-restriction of DKK1
-LP in the presence of different monoclonal antibodies (mAb) specific for HLA-DR, -DQ or HLA-ABC. The results showed that HLA-DR antibody significantly
+
-LP-specific CD8 T-cell response. PBMC stimulated with DKK1
and improved clinical outcome.24 DKK13-76-LP bolstered the induction of DKK1-P20-specific CTL derived from both healthy donors and MM patients in vitro. Thus, DKK13-76-LP administered in combination with DKK1-P20 immunotherapy may be able to augment the elicitation of antigen-specific CTL.
Based on the HLA-subtypes capable of antigen presenta- tion from studies using healthy donors, DKK1-P20 and DKK13-76-LP are predicted to be useful in approximately 80% of the total population. We showed that DKK13-76-LP induced HLA-DP5-, HLA-DR8-, or HLA-DR15-restricted Th cells in healthy donors and also induced HLA-DR- or HLA- DQ-restricted Th cells in MM patients. However, these MM patients were negative for HLA-DP5, -DR8, or -DR15 alleles. We also showed that DKK13-76-LP induced HLA-DR15- or HLA-DQ-restricted Th cells in healthy donors. These results suggest that DKK13-76-LP may encompass Th cell epitopes not previously identified in experiments involving cells derived from healthy donors and DKK13-76-LP may be broadly useful in the majority of MM patients.
Weide et al. reported that the presence of circulating Th cells responding to melanoma antigens Melan-A or NY-ESO-1 has a strong independent prognostic impact on survival among chemotherapy-treated advanced melanoma patients.25 Another study has shown a possible
-LP for -LP in the presence of different mAb specific for HLA-DR, -DQ or HLA-A2. The results showed that HLA-A*0201 antibody sig-
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1 week were re-stimulated with DKK1
ing solid evidence that the phenomenon of epitope spreading is critical to the development of effective anti- cancer immunity elicited by peptide vaccination. These results further implicate functional interactions between vaccine-induced CTL and malignant cells that facilitate the induction of large numbers of tumor-specific CTL, the cytolytic effector immune cells that subsequently destroy tumor cells.
Disis et al. reported that vaccination with a herceptin-2 (HER-2/neu)-derived LP encompassing an HLA-A*0201- restricted CTL epitope elicited embedded CTL-epitope specific CD8+ T cells in cancer patients.8 They showed that tumor-specific CTL can be elicited in vivo via cross- presentation of HER-2/neu-derived LP. Such T-cell responses are considered to be crucial for tumor eradica- tion and for generating long-term memory.23 With this premise in mind, we identified an immunogenic DKK13-76- LP that encompasses both Th epitopes and CTL-epitopes and demonstrated that cross-presentation of DKK13-76-LP induced priming and expansion of DKK1-spe- cific CTL in vitro and in vivo. Vaccination with DKK13-76-LP can potentially elicit combined Th and CTL responses. A recent clinical trial showed that targeting Th cells with DC pulsed with both HLA class I and II-restricted epitopes effectively enhanced vaccine-specific immune responses
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nificantly reduced the percentages of IFN-g-secreting CD8+ T cells. Representative results of three experiments are shown. *P<0.05; **P<0.01.
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haematologica | 2021; 106(3)