Peptide/MHC tetramer-based sorting of CD8? T cells to a leukemia antigen yields clonotypes drawn nonspecifically from an underlying restricted repertoire.

ABSTRACT: Testing of T cell-based cancer therapeutics often involves measuring cancer antigen-specific T-cell populations with the assumption that they arise from in vivo clonal expansion. This analysis, using peptide/MHC tetramers, is often ambiguous. From a leukemia cell line, we identified a CDK4-derived peptide epitope, UNC-CDK4-1 (ALTPVVVTL), that bound HLA-A*02:01 with high affinity and could induce CD8? T-cell responses in vitro. We identified UNC-CDK4-1/HLA-A*02:01 tetramer? populations in 3 of 6 patients with acute myeloid leukemia who had undergone allogeneic stem cell transplantation. Using tetramer-based, single-cell sorting and T-cell receptor ? (TCR?) sequencing, we identified recurrent UNC-CDK4-1 tetramer-associated TCR? clonotypes in a patient with a UNC-CDK4-1 tetramer? population, suggesting in vivo T-cell expansion to UNC-CDK4-1. In parallel, we measured the patient's TCR? repertoire and found it to be highly restricted/oligoclonal. The UNC-CDK4-1 tetramer-associated TCR? clonotypes represented >17% of the entire TCR? repertoire-far in excess of the UNC-CDK4-1 tetramer? frequency-indicating that the recurrent TCR? clonotypes identified from UNC-CDK-4-1 tetramer? cells were likely a consequence of the extremely constrained T-cell repertoire in the patient and not in vivo UNC-CDK4-1-driven clonal T-cell expansion. Mapping recurrent TCR? clonotype sequences onto TCR? repertoires can help confirm or refute antigen-specific T-cell expansion in vivo.

SUBMITTER: Hunsucker SA 

PROVIDER: S-EPMC4351150 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature