T-cell responses directed against multiple HLA-A*0201-restricted epitopes derived from Wilms' tumor 1 protein in patients with leukemia and healthy donors: identification, quantification, and characterization.
OBJECTIVE
Antigens derived from the Wilms' tumor (WT1) protein, which is overexpressed in leukemias, are attractive targets for immunotherapy. Four HLA-A*0201-restricted WT1-derived epitopes have been identified: WT37, WT126, WT187, and WT235. We determined the natural immunogenecity of these antigens in patients with hematologic malignancies and healthy donor.


METHODS
To detect very low frequencies of WT1-specific CD8+ T cells, we used quantitative reverse transcription-PCR to measure IFN-gamma mRNA production by WT1 peptide-pulsed CD8+ T cells from 12 healthy donors, 8 patients with chronic myelogenous leukemia, 6 patients with acute myelogenous leukemia, and 8 patients with acute lymphoblastic leukemia.


RESULTS
Responses were detected in 5 of 8 chronic myelogenous leukemia patients, 4 of 6 patients with acute myelogenous leukemia, and 7 of 12 healthy donors. No responses were detected in patients with acute lymphoblastic leukemia. The magnitude and extent of these CD8+ T-cell responses was greater in patients with myeloid leukemias than in healthy donors. Clonotypic analysis of WT1-specific CD8+ T cells directly ex vivo in one case showed that this naturally occurring population was oligoclonal. Using fluorescent peptide-MHC class I tetramers incorporating mutations in the alpha3 domain (D227K/T228A) that abrogate binding to the CD8 coreceptor, we were able to confirm the presence of high-avidity T-cell clones within the antigen-specific repertoire.


CONCLUSIONS
The natural occurrence of high-avidity WT1-specific CD8+ T cells in the periphery could facilitate vaccination strategies to expand immune responses against myeloid leukemias.
Rezvani
Katayoun
K
Stem Cell Allotransplantation Section, Hematology Branch, National Heart Lung Blood Institute and Vaccine Research Center, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland 20892, USA. rezvanik@nhlbi.nih.gov
Brenchley
Jason M
JM
Price
David A
DA
Kilical
Yasemin
Y
Gostick
Emma
E
Sewell
Andrew K
AK
Li
Jongming
J
Mielke
Stephan
S
Douek
Daniel C
DC
Barrett
A John
AJ
D000595:Amino Acid Sequence; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D045744:Cell Line, Tumor; D015234:HLA-A Antigens / Q000276:immunology*; D015789:HLA-A2 Antigen; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology* / Q000494:pharmacology; D007938:Leukemia / Q000276:immunology*; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000494:pharmacology; D025721:WT1 Proteins / Q000276:immunology* / Q000494:pharmacology
D015234:HLA-A Antigens; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; D016056:Immunodominant Epitopes; D010455:Peptides; D025721:WT1 Proteins