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CD45 enhances positive selection and is expressed at a high level in large, cycling, positively selected CD4 + CD8 + thymocytes
Author(s) -
ONG C. J.,
DUTZ J. P.,
CHUI D.,
TEH H.S.,
MARTH J. D.
Publication year - 1997
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.1997.00216.x
Subject(s) - thymocyte , t cell receptor , cd8 , biology , population , major histocompatibility complex , microbiology and biotechnology , transgene , negative selection , t cell , antigen , immunology , immune system , genetics , gene , demography , genome , sociology
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‐2D b (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.