A Novel Strategy for the Discovery of MHC Class II–Restricted Tumor Antigens: Identification of a Melanotransferrin Helper T-Cell Epitope

Abstract

CD4+ helper T cells play a critical role in orchestrating host immune responses, including antitumor immunity. The limited availability of MHC class II-associated tumor antigens is still viewed as a major obstacle in the use of CD4 + T cells in cancer vaccines. Here, we describe a novel approach for the identification of MHC class II tumor-associated antigens (TAAs). By combining two-dimensional liquid chromatography and nanoelectrospray ionization tandem mass spectrometry, we developed a highly sensitive method for the detection of human leukocyte antigen (HLA)-DR-associated peptides of dendritic cells upon exposure to necrotic tumor cells. This approach led to the identification of a novel MHC class II-restricted TAA epitope derived from melanotransferrin. The epitope stimulated T cells derived from melanoma patients and healthy individuals and displayed promiscuity in HLA-DR restriction. Moreover, the same peptide was also presented by MHC class II-positive melanoma cells. This strategy may contribute to increase the number of tumor epitopes presented by MHC class II molecules and may support the development of more efficacious vaccines against cancer. (Cancer Res 2005; 65(21): 10068-78)

Naturally processed T cell–activating peptides of the major birch pollen allergen

“…Peptide clusters in the regions Bet v 1 22-37 , Bet v 1 33-55 , Bet v 1 56-65 , and Bet v 1 69-80 did not appear before 3 hours of proteolytic cleavage. Remarkably, early appearing peptide clusters matched frequently recognized T cell-activating regions such as Bet v 1 4-15 , Bet v 1 [13][14][15][16][17][18][19][20][21][22][23][24] , Bet v 1 [19][20][21][22][23][24][25][26][27][28][29][30] , Bet v 1 79-90 , Bet v 1 97-108 , Bet v 1 112-123 , and Bet v 1 142-153 previously identified in Bet v 1-specific TCL derived from 58 donors with birch pollen allergy. 23 Bet v 1-derived naturally processed peptides First, the optimum incubation period for appearance of allergen-derived peptides on the surface of Bet v 1-pulsed DCs was evaluated.…”

“…30 For patients 1 to 3, peptides (20 mL) were separated by capillary rpHPLC (Waters) directly coupled to a Q-Tof Global Ultima mass spectrometer (Waters) by using a Nanoflow spray head (precolumn Nanoease Symmetry300 trap column, separating column Nanoease Atlantis dC18; Waters). Peptides were eluted with an acetonitrile gradient (solvent A 0.1% vol/vol formic acid/5% vol/vol acetonitrile; solvent B 0.1% vol/vol formic acid/95% vol/ vol acetonitrile; 5% to 45% B in 90 minutes).…”

“…DCs from patient 2 (HLA-DRB1*0701) presented peptides located within Bet v 1 69-96 . DCs from patient 3 (HLA-DRB1*0101, *0301) presented peptides located within Bet v 1 [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] , and DCs from patient 4 (HLA-DRB1*1501, *1601) presented peptides located within 2 different regions, Bet v 1 [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and Bet v 1 132-159 .…”

Exploiting natural anti-tumor immunity for metastatic renal cell carcinoma

“…16,17 One limitation of peptide-based tumor vaccines is major histocompatibility complex (MHC) restriction, and therefore diminished utility in diverse populations. 18 Suboptimal efficacy could also result from tumor heterogeneity, emergence of tumor cells that lose the targeted antigen, and immunological modulation that limit a productive antitumor immune response. Autologous whole tumor cells include all antigens that a person's immune system could potentially respond to, representing a more exhaustive repertoire of tumor antigens.…”

Immunogenicity of Protein Therapeutics: Risk Assessment and Risk Mitigation

“…This technology allows the identification of truly processed and presented peptide epitopes derived from the cellular source, human dendritic cells, which are responsible for priming of CD4 + T cells in vivo. The MAPPs approach led to the identification of novel helper T-cell epitopes in the context of tumor antigens [38] and T-cell epitopes of the therapeutic protein Betaseron, which are supposed to give rise to neutralizing ATA responses (unpublished results). While the MAPPs technology allows derisking those T-cell epitopes that are predicted by in silico tools rather than being presented to T cells, there is still room for improvement with regard to sample throughput and cost, thereby making this approach less attractive for screening purposes.…”