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Understanding CD8 + T-cell responses toward the native and alternate HLA-A * 02:01-restricted WT1 epitope

View Article: PubMed Central - PubMed

ABSTRACT

Ry: The Wilms' tumor 1 (WT1) antigen is expressed in solid and hematological malignancies, but not healthy tissues, making it a promising target for cancer immunotherapies. Immunodominant WT1 epitopes, the native HLA-A2/WT1126-134 (MFPNAPYL) (HLA-A2/RMFPNAPYL epitope (WT1A)) and its modified variant MFPNAPYL (HLA-A2/YMFPNAPYL epitope (WT1B)), can induce WT1-specific CD8+ T cells, although WT1B is more stably bound to HLA-A*02:01. Here, to further determine the benefits of those two targets, we assessed the naive precursor frequencies; immunogenicity and cross-reactivity of CD8+ T cells directed toward these two WT1 epitopes. Ex vivo naive WT1A- and WT1B-specific CD8+ T cells were detected in healthy HLA-A*02:01+ individuals with comparable precursor frequencies (1 in 105–106) to other naive CD8+ T-cell pools (for example, A2/HIV-Gag77-85), but as expected, ~100 × lower than those found in memory populations (influenza, A2/M158-66; EBV, A2/BMLF1280-288). Importantly, only WT1A-specific naive precursors were detected in HLA-A2.1 mice. To further assess the immunogenicity and recruitment of CD8+ T cells responding to WT1A and WT1B, we immunized HLA-A2.1 mice with either peptide. WT1A immunization elicited numerically higher CD8+ T-cell responses to the native tumor epitope following re-stimulation, although both regimens produced functionally similar responses toward WT1A via cytokine analysis and CD107a expression. Interestingly, however, WT1B immunization generated cross-reactive CD8+ T-cell responses to WT1A and could be further expanded by WT1A peptide revealing two distinct populations of single- and cross-reactive WT1A+CD8+ T cells with unique T-cell receptor-αβ gene signatures. Therefore, although both epitopes are immunogenic, the clinical benefits of WT1B vaccination remains debatable and perhaps both peptides may have separate clinical benefits as treatment targets.

No MeSH data available.


Detection of ex vivo WT1A-specific CD8+ T-cell responses following WT1A or WT1B vaccination of HLA-A2.1 transgenic mice. Schematic of the vaccination schedule is shown in a. In one experiment, mice received four-weekly intradermal injections at the base of tail with WT1A/CpG, WT1B/CpG or the negative control, HPV7-E7/CpG. Seven days following the fourth injection, tetramer staining was performed on iLN or spleen cells. Representative tetramer staining (b) in iLN following WT1A/CpG (n=4), WT1B/CpG (n=4) and control HPV-E7/CpG vaccination (n=3). Percentages of tetramer+CD8+ T cells in iLN (c) and spleen (d) cells from each vaccinated group are gated on total CD8+ T cells (mean±s.d. bars are shown). Reciprocal tetramer staining was not carried out in the spleen (d).
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fig2: Detection of ex vivo WT1A-specific CD8+ T-cell responses following WT1A or WT1B vaccination of HLA-A2.1 transgenic mice. Schematic of the vaccination schedule is shown in a. In one experiment, mice received four-weekly intradermal injections at the base of tail with WT1A/CpG, WT1B/CpG or the negative control, HPV7-E7/CpG. Seven days following the fourth injection, tetramer staining was performed on iLN or spleen cells. Representative tetramer staining (b) in iLN following WT1A/CpG (n=4), WT1B/CpG (n=4) and control HPV-E7/CpG vaccination (n=3). Percentages of tetramer+CD8+ T cells in iLN (c) and spleen (d) cells from each vaccinated group are gated on total CD8+ T cells (mean±s.d. bars are shown). Reciprocal tetramer staining was not carried out in the spleen (d).

Mentions: HLA-A2.1 transgenic mice have previously been utilized for studying CD8+ T-cell responses against WT1A following DNA vaccination.36 However, to date, the immunogenicity of WT1B and the direct comparison between WT1A and WT1B vaccination has not yet been investigated. Thus, to compare the immunogenicity between the native WT1A peptide versus the altered WT1B peptide, three groups of HLA-A2.1 transgenic mice were immunized four times weekly with the appropriate peptide in CpG. The vaccination groups included WT1A/CpG and WT1B/CpG, as well as an HPV-E7/CpG group to control for repeated doses of high CpG amounts (Figure 2a). Cells from inguinal lymph nodes (iLNs) (Figure 2b) and spleen from each mouse were isolated and stained with either WT1A-tetramer (co-stain 1) or WT1B-tetramer (co-stain 2) and an irrelevant SV4-tetramer as a negative control.


Understanding CD8 + T-cell responses toward the native and alternate HLA-A * 02:01-restricted WT1 epitope
Detection of ex vivo WT1A-specific CD8+ T-cell responses following WT1A or WT1B vaccination of HLA-A2.1 transgenic mice. Schematic of the vaccination schedule is shown in a. In one experiment, mice received four-weekly intradermal injections at the base of tail with WT1A/CpG, WT1B/CpG or the negative control, HPV7-E7/CpG. Seven days following the fourth injection, tetramer staining was performed on iLN or spleen cells. Representative tetramer staining (b) in iLN following WT1A/CpG (n=4), WT1B/CpG (n=4) and control HPV-E7/CpG vaccination (n=3). Percentages of tetramer+CD8+ T cells in iLN (c) and spleen (d) cells from each vaccinated group are gated on total CD8+ T cells (mean±s.d. bars are shown). Reciprocal tetramer staining was not carried out in the spleen (d).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5382434&req=5

fig2: Detection of ex vivo WT1A-specific CD8+ T-cell responses following WT1A or WT1B vaccination of HLA-A2.1 transgenic mice. Schematic of the vaccination schedule is shown in a. In one experiment, mice received four-weekly intradermal injections at the base of tail with WT1A/CpG, WT1B/CpG or the negative control, HPV7-E7/CpG. Seven days following the fourth injection, tetramer staining was performed on iLN or spleen cells. Representative tetramer staining (b) in iLN following WT1A/CpG (n=4), WT1B/CpG (n=4) and control HPV-E7/CpG vaccination (n=3). Percentages of tetramer+CD8+ T cells in iLN (c) and spleen (d) cells from each vaccinated group are gated on total CD8+ T cells (mean±s.d. bars are shown). Reciprocal tetramer staining was not carried out in the spleen (d).
Mentions: HLA-A2.1 transgenic mice have previously been utilized for studying CD8+ T-cell responses against WT1A following DNA vaccination.36 However, to date, the immunogenicity of WT1B and the direct comparison between WT1A and WT1B vaccination has not yet been investigated. Thus, to compare the immunogenicity between the native WT1A peptide versus the altered WT1B peptide, three groups of HLA-A2.1 transgenic mice were immunized four times weekly with the appropriate peptide in CpG. The vaccination groups included WT1A/CpG and WT1B/CpG, as well as an HPV-E7/CpG group to control for repeated doses of high CpG amounts (Figure 2a). Cells from inguinal lymph nodes (iLNs) (Figure 2b) and spleen from each mouse were isolated and stained with either WT1A-tetramer (co-stain 1) or WT1B-tetramer (co-stain 2) and an irrelevant SV4-tetramer as a negative control.

View Article: PubMed Central - PubMed

ABSTRACT

Ry: The Wilms' tumor 1 (WT1) antigen is expressed in solid and hematological malignancies, but not healthy tissues, making it a promising target for cancer immunotherapies. Immunodominant WT1 epitopes, the native HLA-A2/WT1126-134 (MFPNAPYL) (HLA-A2/RMFPNAPYL epitope (WT1A)) and its modified variant MFPNAPYL (HLA-A2/YMFPNAPYL epitope (WT1B)), can induce WT1-specific CD8+ T cells, although WT1B is more stably bound to HLA-A*02:01. Here, to further determine the benefits of those two targets, we assessed the naive precursor frequencies; immunogenicity and cross-reactivity of CD8+ T cells directed toward these two WT1 epitopes. Ex vivo naive WT1A- and WT1B-specific CD8+ T cells were detected in healthy HLA-A*02:01+ individuals with comparable precursor frequencies (1 in 105–106) to other naive CD8+ T-cell pools (for example, A2/HIV-Gag77-85), but as expected, ~100 × lower than those found in memory populations (influenza, A2/M158-66; EBV, A2/BMLF1280-288). Importantly, only WT1A-specific naive precursors were detected in HLA-A2.1 mice. To further assess the immunogenicity and recruitment of CD8+ T cells responding to WT1A and WT1B, we immunized HLA-A2.1 mice with either peptide. WT1A immunization elicited numerically higher CD8+ T-cell responses to the native tumor epitope following re-stimulation, although both regimens produced functionally similar responses toward WT1A via cytokine analysis and CD107a expression. Interestingly, however, WT1B immunization generated cross-reactive CD8+ T-cell responses to WT1A and could be further expanded by WT1A peptide revealing two distinct populations of single- and cross-reactive WT1A+CD8+ T cells with unique T-cell receptor-αβ gene signatures. Therefore, although both epitopes are immunogenic, the clinical benefits of WT1B vaccination remains debatable and perhaps both peptides may have separate clinical benefits as treatment targets.

No MeSH data available.