Mass‐spectrometric evaluation of HLA‐A*0201‐associated peptides identifies dominant naturally processed forms of CTL epitopes from MART‐1 and gp100

Skipper, Jonathan; Gulden, Pamela H.; Hendrickson, Ronald C.; Harthun, Nancy L.; Caldwell, John R.; Shabanowitz, Jeffrey; Engelhard, Víctor H.; Hunt, Donald F.; Slingluff, Craig L.

doi:10.1002/(sici)1097-0215(19990827)82:5<669::aid-ijc9>3.0.co;2-#

Cited by 81 publications

(98 citation statements)

References 27 publications

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“…By virtue of the natural CTL response that is used this method as well will result in the identification of mostly immunodominant epitopes, and a systematic search for novel epitopes is impossible. An alternative biochemical approach for defining the unknown specificity of tumor-reactive CTL, which are either induced against tumor cells 83,84 or for example against peptides eluted from tumor cells, 85 starts with the immunoaffinity purification of the HLA class I -peptide complexes from the relevant tumor cell. The peptides are subsequently isolated and fractionated by (multiple rounds of) HPLC to reduce the complexity of the peptide pool.…”

Section: Identification Of Ctl Epitopes Starting With Ctl Of Unknown supporting

confidence: 78%

“…Pinpointing the fraction that contained the epitope through recognition by the CTL together with tandem mass spectrometry (MS/MS)-mediated sequencing of the peptides in that fraction identifies the precise peptide sequence. [83][84][85][86][87][88] Subsequently, database searches may identify the unknown source antigen. [85][86][87][88] A particular advantage of this strategy is that it may identify post-translationally modified epitopes 89,90 (or special epitopes generated by protein/peptide splicing 48,49,91 ).…”

Section: Identification Of Ctl Epitopes Starting With Ctl Of Unknown mentioning

confidence: 99%

“…177 Identification of HLA class I and class II ligands by MS/MS As discussed above, starting from pre-existing CTL with unknown or known specificity, the combination of microscale liquid chromatography coupled to MS/MS with functional immunoassays has been used for the identification or confirmation of tumor-specific CTL epitopes, respectively. [83][84][85][86][87][88][89] Without the availability of an epitope-specific T cell, MS/MS can also be applied for the validation of predicted HLA class I ligands (Figure 2). This alternative reverse immunology strategy was coined the 'predict-calibrate-detect' (PCD) method.…”

Section: Identification Of Hla Class Ii-presented T-helper Epitopesmentioning

confidence: 99%

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Identification of T-cell epitopes for cancer immunotherapy

2007

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The effectiveness of T-cell-mediated immunotherapy of cancer depends on both an optimal immunostimulatory context of the therapy and the proper selection with respect to quality and quantity of the targeted tumor-associated antigens (TAA), and, more precisely, the T-cell epitopes contained in these tumor proteins. Our progressing insight in human leukocyte antigen (HLA) class I and class II antigen processing and presentation mechanisms has improved the prediction by reverse immunology of novel cytotoxic T lymphocyte and T-helper cell epitopes within known antigens. Computer algorithms that in silico predict HLA class I and class II binding, proteasome cleavage patterns and transporter associated with antigen processing translocation are now available to expedite epitope identification. The advent of genomics allows a high-throughput screening for tumor-specific transcripts and mutations, with that identifying novel shared and unique TAA. The increasing power of mass spectrometry and proteomics will lead to the direct identification from the tumor cell surface of numerous novel tumor-specific HLA class I and class II presented ligands. Together, the expanded repertoire of tumor-specific T-cell epitopes will enable more precise immunomonitoring and the development of effective epitope-defined adoptive T-cell transfer and multi-epitope-based vaccination strategies targeting epitopes derived from a wider diversity of TAA presented in a broader array of HLA molecules.

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Section: Identification Of Ctl Epitopes Starting With Ctl Of Unknown supporting

confidence: 78%

Section: Identification Of Ctl Epitopes Starting With Ctl Of Unknown mentioning

confidence: 99%

Section: Identification Of Hla Class Ii-presented T-helper Epitopesmentioning

confidence: 99%

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Identification of T-cell epitopes for cancer immunotherapy

2007

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“…The HLA class I Ag-associated peptides KTWGQYWQV (gp100 154 -162 ) (15), YLEPGPVTA (gp100 280 -288 ) (16), AAGIGILTV (MART-1 [27][28][29][30][31][32][33][34][35] ) (17,18), YMDGTMSQV (Tyr 369 -377D ) (19), GILGFVFTL (influenza matrix protein M1 peptide), and YLKKIKNSL (malaria CSP 334 -342 ) (20) were synthesized with a free amide N terminus and free acid C terminus by standard Fmoc chemistry using a model AMS422 peptide synthesizer (Gilson), and then purified to Ͼ98% purity by reverse-phase HPLC on a C-8 column (Vydac) at the University of Virginia Biomolecular Core Facility. Purity and identity were confirmed using a triple quadrupole mass spectrometer (Finnigan).…”

Section: Peptidesmentioning

confidence: 99%

Sequential Immune Escape and Shifting of T Cell Responses in a Long-Term Survivor of Melanoma

Yamshchikov¹,

Mullins

Chang

et al. 2005

The Journal of Immunology

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Immune-mediated control of tumors may occur, in part, through lysis of malignant cells by CD8+ T cells that recognize specific Ag-HLA class I complexes. However, tumor cell populations may escape T cell responses by immune editing, by preventing formation of those Ag-HLA complexes. It remains unclear whether the human immune system can respond to immune editing and recognize newly arising escape variants. We report an example of shifting immune responses to escape variants in a patient with sequential metastases of melanoma and long-term survival after surgery alone. Tumor cells in the first metastasis escaped immune recognition via selective loss of an HLA haplotype (HLA-A11, -B44, and -Cw17), but maintained expression of HLA-A2. In the second metastasis, immune escape from an immunodominant MART-1-specific T cell response was mediated by HLA class I down-regulation, resulting in a failure to present this epitope, but persistent presentation of a tyrosinase-derived epitope. Consequent to this modification in tumor Ag presentation, the dominant CTL response shifted principally toward a tyrosinase-targeted response, even though tyrosinase-specific CTL had been undetectable during the initial metastatic event. Thus, in response to immune editing of tumor cells, a patient’s spontaneous T cell response adapted, gaining the ability to recognize and to lyse “edited” tumor targets. The observation of both immune editing and immune adaptation in a patient with long-term survival after surgery alone demonstrates an example of immune system reactivity to counteract the escape mechanism(s) developed by tumor cells, which may contribute to the clinical outcome of malignant disease.

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“…In vitro studies employing high-affinity MART-1-specific CD8 + T-cell clones demonstrated that some melanoma cell lines, despite expression of MART-1 and the corresponding HLA allele, were only barely recognized by specific T cells [3]. While different variants of the MART-1 epitope (including the MART-1 [26][27][28][29][30][31][32][33][34][35] 10-mer and the MART-1 27-35 9-mer) have been identified, only the 9-mer epitope can be eluted in significant amounts from the cell surface of melanoma cells [4]. This suggests that mechanisms related to antigen processing interfere with efficient generation of the 10-mer MART-1 [26][27][28][29][30][31][32][33][34][35] epitope in tumor cells.…”

Section: Introductionmentioning

confidence: 99%

The proteasome immunosubunits, PA28 and ER‐aminopeptidase 1 protect melanoma cells from efficient MART‐1_26‐35‐specific T‐cell recognition

et al. 2015

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Eur. J. Immunol. 2015. 45: 3257-3268 IntroductionThe differentiation antigen melanoma antigen recognized by T cells/melanoma antigen A (thereafter named MART-1) has been a major target in antigen-specific immunotherapy of malignant melanoma and in particular its immunodominant HLA-A*0201-restricted CD8 + T-cell epitope MART-1 26(27)-35 [1,2]. But clinical efficacy of different MART-1-specific therapies has only been limited. In vitro studies employing high-affinity MART-1-specific CD8 + T-cell clones demonstrated that some melanoma cell lines, despite expression of MART-1 and the corresponding HLA allele, were only barely recognized by specific T cells [3]. While different variants of the MART-1 epitope (including the MART-1 [26][27][28][29][30][31][32][33][34][35] 10-mer and the MART-1 27-35 9-mer) have been identified, only the 9-mer epitope can be eluted in significant amounts from the cell surface of melanoma cells [4]. This suggests that mechanisms related to antigen processing interfere with efficient generation of the 10-mer MART-1 26-35 epitope in tumor cells. It has been demonstrated that MART-1 26-35 epitope processing is controlled by the proteasome, the major proteolytic machinery of the cytosol [5]. The standard proteasome (SP) contains the catalytic subunits β1, β2, and β5, whereas exposure of cells to IFN-γ enhances expression and incorporation of the immunosubunits β1i/LMP2 (LMP, low molecular weight protein), β2i/MECL-1 (multicatalytic endopeptidase complex-like 1), and β5i/LMP7 into nascent proteasome complexes. Immunosubunit-containing proteasomes represent catalytic properties that are different from that of SPs [6]. Interestingly, IFN-γ has been described to interfere with efficient MART-1 26-35 epitope generation due to the activity of the proteasome immunosubunits β1i/LMP2 and β5i/LMP7 [5,7,8].To degrade cellular proteins in an ubiquitin-dependent manner, 20S catalytic core particles are connected to 19S regulatory complexes. In the presence of IFN-γ, the expression of PA28α/β (PA, proteasome activator), an activator complex that in combination with the 19S regulatory complex and the 20S proteasome forms so-called PA28-20S-19S hybrid proteasome complexes, is induced [9,10]. The PA28 has been associated with positive effects on epitope processing due to facilitating the access of substrates to the active sites of the proteasome. Generation of the TRP2 360-368 epitope derived from the melanoma antigen tyrosinase-related protein 2 (TRP2) was shown to be completely dependent on PA28 activity by influencing the proteasomal structure and cleavage specificity [11]. Moreover, IFN-γ induces the expression of the ER-resident aminopeptidases ERAP1/2 that trim epitope precursor peptides released into the ER to bind MHC class I molecules [12][13][14][15]. In this context, increased epitope generation has been preferentially attributed to ERAP1, whereas the role of ERAP2 in epitope processing is still under debate [16]. Varying expression levels of ERAP1/2 have been described in different tumor enti...

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Mass‐spectrometric evaluation of HLA‐A*0201‐associated peptides identifies dominant naturally processed forms of CTL epitopes from MART‐1 and gp100

Cited by 81 publications

References 27 publications

Identification of T-cell epitopes for cancer immunotherapy

Identification of T-cell epitopes for cancer immunotherapy

Sequential Immune Escape and Shifting of T Cell Responses in a Long-Term Survivor of Melanoma

The proteasome immunosubunits, PA28 and ER‐aminopeptidase 1 protect melanoma cells from efficient MART‐1_26‐35‐specific T‐cell recognition

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Mass‐spectrometric evaluation of HLA‐A*0201‐associated peptides identifies dominant naturally processed forms of CTL epitopes from MART‐1 and gp100

Cited by 81 publications

References 27 publications

Identification of T-cell epitopes for cancer immunotherapy

Identification of T-cell epitopes for cancer immunotherapy

Sequential Immune Escape and Shifting of T Cell Responses in a Long-Term Survivor of Melanoma

The proteasome immunosubunits, PA28 and ER‐aminopeptidase 1 protect melanoma cells from efficient MART‐126‐35‐specific T‐cell recognition

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The proteasome immunosubunits, PA28 and ER‐aminopeptidase 1 protect melanoma cells from efficient MART‐1_26‐35‐specific T‐cell recognition