CD45 enhances positive selection and is expressed at a high level in large, cycling, positively selected CD4+CD8+ thymocytes.
Immunology
; 91(1): 95-103, 1997 May.
Article
em En
| MEDLINE
| ID: mdl-9203971
ABSTRACT
T-cell development is arrested at the CD4+CD8+ (DP; double-positive) stage of thymocyte development in CD45 null mice. However, the mechanism by which CD45 participates in the positive selection of T cells remains to be investigated. In this report we describe a DP thymocyte population that associates positive selection with expression of high levels of CD45, CD4 and CD8. DP thymocytes of this phenotype are large, cycling cells and represent approximately 20% of DP thymocytes in normal mice. In mice expressing a transgenic T-cell receptor (TCR) specific for the male antigen presented by H-2Db (H-Y TCR), the up-regulation of TCR, CD5 and CD69 in this large DP population occurred in a major histocompatibility complex (MHC)-restricted manner. To investigate further the role of CD45 in positive selection, we determined whether thymocytes that expressed a transgenic CD45RO molecule under the control of the proximal lck promoter can influence the positive selection of T cells in H-Y TCR transgenic mice. It was found that in female H-Y TCR transgenic mice, MHC-restricted positive selection of CD4- CD8+ H-Y TCR+ thymocytes was enhanced by increased CD45RO expression. Thus, CD45 increases the efficacy of positive selection of CD4- CD8+ thymocytes that express H-Y TCR.
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Base de dados:
MEDLINE
Assunto principal:
Timo
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Linfócitos T CD4-Positivos
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Antígenos Comuns de Leucócito
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Linfócitos T CD8-Positivos
Idioma:
En
Ano de publicação:
1997
Tipo de documento:
Article