T cells recognizing a peptide contaminant undetectable by mass spectrometry

Vedran Brezar (1) , Slobodan Culina (1) , Thomas Østerbye (2) , François Guillonneau (3) , Giovanni Chiappetta (4) , Yann Verdier (4) , Joelle Vinh (4) , F. Susan Wong (5) , Søren Buus (2) , Roberto Mallone (1, 6)

1 U986 - Immunologie et génétique du diabète de type 1, génétique multifactorielle en endocrinologie pédiatrique
2 Laboratory of Experimental Immunology [Copenhagen]
3 3P5 - Plateforme protéomique 3P5 [Institut Cochin]
4 SMBP - Spectrométrie de Masse Biologique et Protéomique (USR3149 / FRE2032)
5 Centre for Endocrine and Diabetes Sciences
6 Service de diabétologie [CHU Cochin]

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.

Domaines: Immunité adaptative

Vedran Brezar, Slobodan Culina, Thomas Østerbye, François Guillonneau, Giovanni Chiappetta, et al.. T cells recognizing a peptide contaminant undetectable by mass spectrometry. PLoS ONE, 2011, 6 (12), pp.e28866. ⟨10.1371/journal.pone.0028866⟩. ⟨hal-00858150⟩