Identification of an HLA-A*0201 cytotoxic T lymphocyte epitope specific to the endothelial antigen Tie-2.
Tie-2 stabilises pericyte-endothelial interactions during angiogenesis and is highly expressed on endothelium during several diseases, including arthritis, age-related macular degeneration and cancer. A vaccine that targets endothelium overexpressing Tie-2 may result in vessel damage and stimulate an inflammatory cascade resulting in disease regression. We have identified a region unique to Tie-2 (amino acids 1-196) that is homologous in humans and mice. Using computer algorithms, several HLA-A*0201 epitopes that are identical in mice and humans were predicted within this region; however, binding assays showed that the majority of these epitopes were of low affinity. Modification of the anchor residues of 4 epitopes enhanced HLA binding. These epitopes were incorporated by site-directed mutagenesis into a Tie-2 DNA construct. Immunisation of HLA*0201 transgenic mice with one of the modified Tie-2 constructs stimulated CTLs that recognised both wild-type and modified peptide-pulsed target cells. In contrast, no CTLs were generated in mice immunised with wild-type Tie-2 construct, demonstrating that the modified epitope was necessary in the generation of CTLs. Moreover, CTLs from mice immunised with the modified construct killed HLA-A*0201 endothelial cells overexpressing Tie-2. Our study demonstrates that it is possible to break tolerance to the endothelial antigen Tie-2, suggesting that it may be feasible to design a vaccine to activate CTLs to kill endothelial cells overexpressing Tie-2.
Ramage
Judith M
JM
Cancer Research UK, Academic Unit of Clinical Oncology, University of Nottingham, City Hospital, Nottingham, United Kingdom. judith.ramage@nottingham.ac.uk
Metheringham
Rachael
R
Conn
Andrew
A
Spendlove
Ian
I
Moss
Robert S
RS
Patton
Daniel T
DT
Murray
J Clifford
JC
Rees
Robert C
RC
Durrant
Lindy G
LG
D000818:Animals; D001483:Base Sequence; D019496:Cancer Vaccines / Q000276:immunology; D042783:Endothelial Cells / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte; D005260:Female; D015234:HLA-A Antigens / Q000502:physiology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D042787:Receptor, TIE-2 / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D015234:HLA-A Antigens; D042787:Receptor, TIE-2