N-linked carbohydrates in tyrosinase are required for its recognition by human MHC class II-restricted CD4+ T cells

Franck Housseau, Anitha Moorthy, Daniel A. Langer, Paul F. Robbins, Monica I. Gonzales, Suzanne L. Topalian

Research output: Contribution to journalArticle

Abstract

Glycosylation of mammalian proteins is known to influence their intracellular trafficking, half life, and susceptibility to enzymatic degradation. Rare instances of natural T cell epitopes dependent upon glycosylation for recognition have been described. We report here on human CD4+ T lymphocyte cultures and clones from two melanoma patients that recognize the melanoma-associated Ag tyrosinase in the context of HLA-DR4 and -DR8. These T cells recognize tyrosinase, normally a heavily glycosylated molecule, when expressed constitutively in melanoma cells or in COS-7 transfectants pulsed as lysates onto autologous APC. However, these T cells fail to recognize tyrosinase expressed in bacteria, nor do they react with overlapping peptides covering full-length tyrosinase, suggesting a critical role for glycosylation in the processing and/or composition of the stimulatory epitopes. The requirement for glycosylation was demonstrated by the failure of tyrosinase-specific CD4+ T cells to recognize tyrosinase synthesized in the presence of glycosylation inhibitors, or deglycosylated enzymatically. Site-directed mutagenesis of each of seven potential N-glycosylation sites showed that four sites were required to generate forms of tyrosinase that could be recognized by individual T cell clones. These data indicate that certain carbohydrate moieties are required for processing the tyrosinase peptides recognized by CD4+ T cells. Post-translational modifications of human tumor-associated proteins such as tyrosinase could be a critical factor for the development of antitumor immune responses.

Original languageEnglish (US)
Pages (from-to)2690-2701
Number of pages12
JournalEuropean Journal of Immunology
Volume31
Issue number9
DOIs
StatePublished - Jan 1 2001
Externally publishedYes

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Keywords

  • Antigen processing
  • MHC
  • T lymphocyte
  • Tumor immunity

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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