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Thymocytes positively select thymocytes in human system
1Department of Pathology, Seoul National University College of Medicine, Korea.
Human Immunology
|April 15, 1997
Summary
Human thymocytes expressing MHC class II molecules actively participate in T cell selection. Blocking T cell receptor recognition of MHC class II molecules arrests T cell maturation.
Area of Science:
- Immunology
- Cell Biology
Background:
- MHC class II molecules are expressed on human fetal and postnatal thymocytes.
- Previous findings raised questions about the role of these molecules in immature T cell selection.
Purpose of the Study:
- To investigate the active involvement of MHC class II+ thymocytes in T cell selection.
- To determine the role of T-T interactions in T cell maturation.
Main Methods:
- Development of a human reaggregate culture system.
- Analysis of T cell maturation and differentiation stages.
- Blocking of T cell receptor (TCR) recognition of MHC class II molecules.
Main Results:
- MHC class II+ thymocytes, not just thymic epithelial cells, are involved in T cell selection via T-T interaction.
- Maturation to single positive (SP) cells requires MHC class II molecules.
- Blocking TCR recognition of MHC class II molecules arrested T cells at the double positive (DP) stage.
Conclusions:
- Human MHC class II+ thymocytes play an active role in selecting the T cell receptor (TCR) repertoire.
- TCR recognition of peptide/MHC class II is a critical initial step in T cell selection.