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Role of CD4 molecule in intrathymic T-cell development
Y Takeuchi1, T Horiuchi, K Hamamura
1Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Immunology
|October 1, 1991
Summary
CD4 molecules are essential for positive selection of thymocytes but play a partial role in negative selection. Blocking CD4 impacts T-cell development, suggesting CD4-mediated thymic selection of T-cell receptor alpha beta-bearing CD4-8- cells.
Area of Science:
- Immunology
- Cell Biology
- Developmental Biology
Background:
- T-cell repertoire selection occurs in the thymus.
- CD4 and CD8 are key co-receptors in T-cell development.
- Thymic selection ensures self-tolerance and generates functional T cells.
Purpose of the Study:
- To investigate the role of CD4 molecules in intrathymic T-cell repertoire selection.
- To determine CD4's contribution to positive and negative selection.
- To elucidate the developmental pathways of T-cell receptor alpha beta-bearing CD4-8- cells.
Main Methods:
- Murine fetal thymus organ culture (FTOC).
- Administration of anti-CD4 and anti-class II MHC (Ia) monoclonal antibodies (mAbs).
- Monitoring of T-cell receptor (TCR) V beta gene product expression and cell populations (CD4+8-, CD4-8+, CD4+8+, CD4-8-).
Main Results:
- Anti-CD4 mAb treatment completely inhibited CD4+8- cell development.
- Anti-CD4 partially restored V beta 8+ cell depletion, enhanced by anti-Ia mAb.
- Anti-CD4 treatment led to the appearance of V beta 6-bearing cells in various populations, including CD4-8- cells.
Conclusions:
- CD4 is indispensable for positive selection of CD4+8- thymocytes.
- CD4's role in negative selection is partial.
- CD4-8- T-cell receptor alpha beta-bearing cells may originate from CD4+ cells and undergo CD4-mediated thymic selection.