The contributions of mass spectrometry to understanding of immune recognition by T lymphocytes

Abstract

Over the last 15 years, the ability of mass spectrometry to analyze complex peptide mixtures and identify individual species has provided unprecedented insights into the repertoire of peptide antigens displayed by MHC molecules and recognized by T lymphocytes. These include: understanding the peptide binding specificity of MHC molecules; understanding of roles of different intracellular components of the antigen processing pathways in determining the peptide display; and identification of a large number of individual peptide antigens associated with infectious diseases, cancer, and transplant rejection that have provided the basis for new immunologically based therapies. This review will summarize the impact that the application of mass spectrometry has had on these advances, with particular attention to the contributions of Professor Donald Hunt and members of his laboratory, and point out the opportunities for future work. Keywordsantigen processing; post-translational modification; peptides; MHC molecules THE NATURE OF ANTIGEN RECOGNITION BY T LYMPHOCYTEST lymphocytes are a branch of the immune system concerned with recognition of antigens that are displayed on the surface of host cells. These antigens are produced through intracellular proteolytic mechanisms that create small peptides, which are then rescued and presented at the cell surface by adaptor proteins called MHC molecules [reviewed in [1-6]. The binding site of each MHC molecule enables it to bind to a wide range of different peptides, and results in the display of a repertoire of such antigens, each recognized by a distinct T lymphocyte. This "antigen processing and presentation" mechanism results in the display of peptides derived from the proteins of pathogens that have infected the cell or been taken up by endocytosis. Their recognition by T lymphocytes results in the development of an immune response, and results in clearance of the pathogen and infected cells from the body. However, antigen processing and presentation pathways operate constitutively on normal cellular proteins as well, resulting in the display of peptide antigens that can be distinguished on tumors and transplanted tissues. Some of these "self-peptides" are also involved in the development of T lymphocytes in the thymus, and their recognition also controls the balance between selftolerance and autoimmune disease. Correspondence: phone: 434-924-2423; fax: 434-924-1221; email: vhe@virginia.edu Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. In most individuals, molecules of each MHC class are expressed from 3 genetic loci that ...

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