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Differential thymus dependence of rat CD8 isoform expression.
N Torres-Nagel1, E Kraus, M H Brown
1Institut für Virologie und Immunbiologie, Universität Würzburg, FRG.
European Journal of Immunology
|November 1, 1992
Summary
Rat CD8 molecule expression differs between T cells and NK cells. CD8 alpha/beta heterodimers are thymus-dependent, while CD8 alpha homodimers appear on activated cells and NK cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- The CD8 molecule is a co-receptor crucial for T cell recognition of antigens presented by MHC class I molecules.
- Understanding CD8 expression patterns is vital for dissecting immune cell subsets and their functions.
Purpose of the Study:
- To investigate the expression patterns of CD8 isoforms (alpha/beta heterodimer and alpha homodimer) in rat immune cells.
- To differentiate CD8 expression in T cells, NK cells, and cells from specific tissues like the gut.
Main Methods:
- Utilized five novel monoclonal antibodies (mAbs) to characterize CD8 alpha and beta chains.
- Employed flow cytometry to analyze CD8 expression on T cells and NK cells from various rat tissues.
- Investigated CD8 expression on activated T cells and intestinal intraepithelial lymphocytes (IEL).
Main Results:
- Rat peripheral T cells predominantly express the CD8 alpha/beta heterodimer, irrespective of T cell receptor (TCR) type.
- Natural killer (NK) cells exclusively express CD8 alpha chains (CD8 alpha+ beta-).
- CD8 alpha homodimers are found on activated T cells and a significant subset of intestinal IEL, suggesting local activation.
Conclusions:
- CD8 alpha/beta heterodimer expression is thymus-dependent, indicating a role for intrathymic maturation.
- CD8 alpha homodimer expression is less thymus-dependent and observed in activated T cells, NK cells, and gut IEL.
- The MHC class I restriction of gamma/delta T cells may be linked to their CD8 alpha/beta+ phenotype.