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Updated: May 26, 2026

Peptide:MHC Tetramer-based Enrichment of Epitope-specific T cells
Published on: October 22, 2012
T cells recognizing a peptide contaminant undetectable by mass spectrometry
Vedran Brezar1, Slobodan Culina, Thomas Østerbye
1INSERM, U986, DeAR Lab Avenir, Saint Vincent de Paul Hospital, Paris, France.
Abstract:
Synthetic peptides are widely used in immunological research as epitopes to stimulate their cognate T cells. These preparations are never completely pure, but trace contaminants are commonly revealed by mass spectrometry quality controls. In an effort to characterize novel major histocompatibility complex (MHC) Class I-restricted β-cell epitopes in non-obese diabetic (NOD) mice, we identified islet-infiltrating CD8+ T cells recognizing a contaminating peptide. The amount of this contaminant was so small to be undetectable by direct mass spectrometry. Only after concentration by liquid chromatography, we observed a mass peak corresponding to an immunodominant islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)(206-214) epitope described in the literature. Generation of CD8+ T-cell clones recognizing IGRP(206-214) using a novel method confirmed the identity of the contaminant, further underlining the immunodominance of IGRP(206-214). If left undetected, minute impurities in synthetic peptide preparations may thus give spurious results.
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