Poor immunogenicity of a self/tumor antigen derives from peptide–MHC-I instability and is independent of tolerance
Zhiya Yu, … , Brian M. Baker, Nicholas P. Restifo
Zhiya Yu, … , Brian M. Baker, Nicholas P. Restifo
Published August 16, 2004
Citation Information: J Clin Invest. 2004;114(4):551-559. https://doi.org/10.1172/JCI21695.
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Article Immunology

Poor immunogenicity of a self/tumor antigen derives from peptide–MHC-I instability and is independent of tolerance

Abstract

Understanding the mechanisms underlying the poor immunogenicity of human self/tumor antigens is challenging because of experimental limitations in humans. Here, we developed a human-mouse chimeric model that allows us to investigate the roles of the frequency and self-reactivity of antigen-specific T cells in determination of the immunogenicity of an epitope (amino acids 209–217) derived from a human melanoma antigen, gp100. In these transgenic mice, CD8+ T cells express the variable regions of a human T cell receptor (hTCR) specific for an HLA-A*0201–restricted gp100209–217. Immunization of hTCR-transgenic mice with gp100209–217 peptide elicited minimal T cell responses, even in mice in which the epitope was knocked out. Conversely, a modified epitope, gp100209–217(2M), was significantly more immunogenic. Both biological and physical assays revealed a fast rate of dissociation of the native peptide from the HLA-A*0201 molecule and a considerably slower rate of dissociation of the modified peptide. In vivo, the time allowed for dissociation of peptide-MHC complexes on APCs prior to their exposure to T cells significantly affected the induction of immune responses. These findings indicate that the poor immunogenicity of some self/tumor antigens is due to the instability of the peptide-MHC complex rather than to the continual deletion or tolerization of self-reactive T cells.

Authors

Zhiya Yu, Marc R. Theoret, Christopher E. Touloukian, Deborah R. Surman, Scott C. Garman, Lionel Feigenbaum, Tiffany K. Baxter, Brian M. Baker, Nicholas P. Restifo

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Figure 3

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Native gp100209–217 peptide fails to activate JR209-Tg T cells in both g...
Native gp100209–217 peptide fails to activate JR209-Tg T cells in both gp100209–217WT and gp100209–217KO mice. (A) Ex vivo antigen-specific proliferative responses of freshly isolated splenocytes from JR209-Tg mice with and without gp100209–217 epitope expression. CFSE-labeled splenocytes were cultured in media containing 1 μM of gp100209–217 or gp100154–162 peptide for 48 hours before FACS. The dot plots represent 10,000 total events in each sample. (B) gp100209–217 peptide–specific IFN-γ release in cells from draining lymph nodes (pooled from two mice in each group) after various doses of gp100209–217(2M) and gp100209–217 peptide immunization in JR209-Tg mice with (white bars) and without (black bars) the epitope expression. Draining lymph nodes were collected 7 days after immunization. One micromole of gp100209–217 peptide was added to 1 × 105 cells in 200 μl of culture media and incubated for 24 hours. IFN-γ concentrations in the supernatant were determined by ELISA. (C) In vivo antigen-specific proliferative responses of adoptively transferred freshly isolated splenocytes from JR209-Tg mice with and without gp100209–217 epitope expression. CFSE-labeled splenocytes (1 × 107) from JR209-Tg–gp100209–217WT or JR209-Tg–gp100209–217KO mice were intravenously injected into A2/Kb recipient mice, followed by immunization (into the footpad) with 100 μg of gp100209–217(2M), gp100209–217 peptide, or PBS (in IFA). Four days after immunization, the cells of draining lymph nodes were pooled from two mice in each group and gated on hVβ8+CD8+ T cells for FACS analysis.