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Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant
Previous studies have demonstrated that insulin, like other protein antigens, requires processing in metabolically active antigen- presenting cells (APC) before it can be recognized by class II- restricted T lymphocytes. Unlike many other proteins, insulin peptides of minimal size retain the require...
Formato: | Texto |
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Lenguaje: | English |
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The Rockefeller University Press
1991
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119004/ https://www.ncbi.nlm.nih.gov/pubmed/1940793 |
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collection | PubMed |
description | Previous studies have demonstrated that insulin, like other protein antigens, requires processing in metabolically active antigen- presenting cells (APC) before it can be recognized by class II- restricted T lymphocytes. Unlike many other proteins, insulin peptides of minimal size retain the requirement for antigen processing. We demonstrate that this requirement can be bypassed by incubation of insulin with reducing agents in the presence of aldehyde-fixed APC. Fixed APC treated in this way were able to stimulate I-Ab- and I-Ad- restricted T cell hybridomas. Data are presented that demonstrate that cloned and polyclonal T cells recognize a determinant within the NH2- terminal 14 residues of the beef insulin A chain with no requirement for B chain residues. The common feature among peptides capable of stimulating these cells in the presence of live APC is the chemical form of the cysteine thiol groups. Those forms that produce free thiols upon reduction are active, whereas those with irreversibly protected sulfhydryls are not. Functional experiments with fixed APC and competition binding experiments with purified I-Ad indicate that only A chain peptides with free thiols are able to stably associate with the peptide-binding site on class II in a form that is recognized by specific T cells. Our findings indicate that reduction of disulfide bonds is both necessary and sufficient for presentation of insulin to a major population of class II-restricted T cells. The results provide strong support for the hypothesis that protein disulfides can be reduced during physiologic antigen processing. |
format | Text |
id | pubmed-2119004 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1991 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-21190042008-04-17 Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant J Exp Med Articles Previous studies have demonstrated that insulin, like other protein antigens, requires processing in metabolically active antigen- presenting cells (APC) before it can be recognized by class II- restricted T lymphocytes. Unlike many other proteins, insulin peptides of minimal size retain the requirement for antigen processing. We demonstrate that this requirement can be bypassed by incubation of insulin with reducing agents in the presence of aldehyde-fixed APC. Fixed APC treated in this way were able to stimulate I-Ab- and I-Ad- restricted T cell hybridomas. Data are presented that demonstrate that cloned and polyclonal T cells recognize a determinant within the NH2- terminal 14 residues of the beef insulin A chain with no requirement for B chain residues. The common feature among peptides capable of stimulating these cells in the presence of live APC is the chemical form of the cysteine thiol groups. Those forms that produce free thiols upon reduction are active, whereas those with irreversibly protected sulfhydryls are not. Functional experiments with fixed APC and competition binding experiments with purified I-Ad indicate that only A chain peptides with free thiols are able to stably associate with the peptide-binding site on class II in a form that is recognized by specific T cells. Our findings indicate that reduction of disulfide bonds is both necessary and sufficient for presentation of insulin to a major population of class II-restricted T cells. The results provide strong support for the hypothesis that protein disulfides can be reduced during physiologic antigen processing. The Rockefeller University Press 1991-11-01 /pmc/articles/PMC2119004/ /pubmed/1940793 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Articles Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title | Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title_full | Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title_fullStr | Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title_full_unstemmed | Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title_short | Reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
title_sort | reduction of disulfide bonds during antigen processing: evidence from a thiol-dependent insulin determinant |
topic | Articles |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2119004/ https://www.ncbi.nlm.nih.gov/pubmed/1940793 |