Linked Life Data

8977176

Source:http://linkedlifedata.com/resource/pubmed/id/8977176

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-1-30
pubmed:abstractText
Immature CD4/CD8 double-positive (DP) thymocytes expressing self MHC-restricted TCR are positively selected in response to TCR signals to survive and differentiate into functionally competent CD4 or CD8 single positive (SP) T cells. In contrast, DP precursors expressing autoreactive TCR are clonally deleted in response to TCR signals. We show here that in vitro TCR engagement of TCR(low) DP thymocytes rapidly triggers a variety of events considered to be hallmarks of positive selection in vivo. These include increased expression of CD5 and Bcl-2, termination of RAG-1 and pre-T(alpha) gene expression, and a switch in lck promoter usage. We also demonstrate that CD4- or CD28-mediated signals synergize with TCR signals to induce these outcomes. Finally, we show that the response of DP thymocytes to TCR engagement is selective in that clonal deletion, CD4/CD8 lineage commitment, and other events associated with maturation, such as changes in expression of Thy-1, HSA, MHC class I, and CD45-RB, were not induced. Thus, only subsets of maturational processes associated with positive selection in vivo were shown to be directly coupled to TCR signaling pathways at the DP stage. These observations support conclusions from in vivo systems suggesting that multiple, temporally separated TCR engagements are required to effect the entire spectrum of developmental changes associated with positive selection, and provide a conceptual and experimental framework for unraveling the complexity of positive selection.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-1767
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
158
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
65-75
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
TCR engagement of CD4+CD8+ thymocytes in vitro induces early aspects of positive selection, but not apoptosis.
pubmed:affiliation
Division of Immunology and Cancer, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't