Human CD4+ T lymphocytes recognize a vascular endothelial growth factor receptor-2-derived epitope in association with HLA-DR.
OBJECTIVE
Given the multiple escape mechanisms of tumor cells, immunotherapy targeting tumor-dependent stroma may be an effective cancer treatment strategy. Animal models indicate that inducing immunity to tumor endothelia engenders potent antitumor effects without significant pathology. Recently, the first human tumor endothelial antigen vascular endothelial growth factor receptor-2 (VEGFR-2) recognized by HLA class I-restricted CD8(+) T cells has been characterized. In this study, we sought to investigate specific recognition of this molecule by human CD4(+) T cells.


METHODS
To identify HLA-DR-restricted antigenic peptides on VEGFR-2 recognized by CD4(+) T cells of healthy donors and cancer patients.


RESULTS
Nine candidate VEGFR-2 peptides with high binding probability to six common HLA-DRB1 alleles were synthesized using the SYFPEITHI algorithm. One 15-mer peptide (EKRFVPDGNRISWDS), mapping to the 167-181 region of VEGFR-2, stimulated CD4(+) T cells in association with several HLA-DR alleles, including DR4 and DR7. Importantly, the epitope could be naturally processed and presented both by HLA-DR-matched antigen-expressing proliferating endothelial cells and by dendritic cells loaded with the native antigen. Furthermore, circulating VEGFR-2-specific CD4(+) T cells were detected in 4 of 10 healthy donors and 12 of 40 cancer patients even after single-round peptide stimulation in short-term culture. Patient's T cells could recognize antigen-expressing proliferating endothelial cells in a HLA-DR-restricted fashion.


CONCLUSIONS
These findings indicate an important role for the 167-181 region of VEGFR-2 in the stimulation of CD4(+) T cell responses to VEGFR-2 protein, and may be instrumental both for the development and monitoring of upcoming antitumor vessel vaccines against different cancers based on VEGFR-2 immunogens.
Sun
Yuansheng
Y
Division of Medical Biotechnology, Paul-Ehrlich-Institute, Langen, Germany. sunyu@pei.de
Song
Mingxia
M
Jäger
Elke
E
Schwer
Christina
C
Stevanovic
Stefan
S
Flindt
Sven
S
Karbach
Julia
J
Nguyen
Xuan D
XD
Schadendorf
Dirk
D
Cichutek
Klaus
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology; D000939:Epitopes / Q000737:chemistry; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006684:HLA-DR Antigens / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000737:chemistry*
D000939:Epitopes; D006684:HLA-DR Antigens; D040301:Vascular Endothelial Growth Factor Receptor-2