Experimental models demonstrated that therapeutic induction of CD8 T cell responses may offer protection against tumors or infectious diseases providing that T cells have sufficiently high TCR/CD8:pMHC avidity for efficient Ag recognition and consequently strong immune functions. However, comprehensive characterization of TCR/CD8:pMHC avidity in clinically relevant situations has remained elusive. In this study, using the novel NTA-His tag–containing multimer technology, we quantified the TCR:pMHC dissociation rates (koff) of tumor-specific vaccine-induced CD8 T cell clones (n = 139) derived from seven melanoma patients vaccinated with IFA, CpG, and the native/EAA or analog/ELA Melan-AMART-126–35 peptide, binding with low or high affinity to MHC, respectively. We observed substantial correlations between koff and Ca2+ mobilization (p = 0.016) and target cell recognition (p < 0.0001), with the latter independently of the T cell differentiation state. Our strategy was successful in demonstrating that the type of peptide impacted on TCR/CD8:pMHC avidity, as tumor-reactive T cell clones derived from patients vaccinated with the low-affinity (native) peptide expressed slower koff rates than those derived from patients vaccinated with the high-affinity (analog) peptide (p < 0.0001). Furthermore, we observed that the low-affinity peptide promoted the selective differentiation of tumor-specific T cells bearing TCRs with high TCR/CD8:pMHC avidity (p < 0.0001). Altogether, TCR:pMHC interaction kinetics correlated strongly with T cell functions. Our study demonstrates the feasibility and usefulness of TCR/CD8:pMHC avidity assessment by NTA-His tag–containing multimers of naturally occurring polyclonal T cell responses, which represents a strong asset for the development of immunotherapy.
This work was supported by the Swiss National Science Foundation (310030-129670); the Canadian Institute of Health Research; and the Ludwig Cancer Research Institute, the Cancer Vaccine Collaborative, and the Cancer Research Institute (all three in New York, NY).
The online version of this article contains supplemental material.
- Received December 22, 2014.
- Accepted April 28, 2015.
- Copyright © 2015 by The American Association of Immunologists, Inc.