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Negative selection by endogenous antigen and superantigen occurs at multiple thymic sites
1MRC Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
International Immunology
|September 1, 1996
Summary
Negative selection of T cells in the thymus is not solely in the cortex. Apoptosis sites vary depending on the trigger, with self-peptides causing deletion in the cortex, medulla, or both.
Area of Science:
- Immunology
- Developmental Biology
- Cell Biology
Background:
- The thymus is the primary site for T cell maturation and selection.
- Negative selection eliminates self-reactive T cells to prevent autoimmunity.
- Previous studies suggested thymic cortex or medulla as the predominant site for negative selection.
Purpose of the Study:
- To investigate the anatomical sites of thymocyte apoptosis during negative selection.
- To compare deletion sites induced by endogenous superantigens versus cognate self-peptides.
- To clarify the location of negative selection within the thymus.
Main Methods:
- Utilized a panel of T cell receptor (TCR) transgenic mouse lines.
- Employed TUNEL staining to visualize apoptotic thymocytes in situ.
- Analyzed deletion sites induced by Mtv superantigens and cognate self-peptides.
Main Results:
- Thymocyte apoptosis induced by Mtv superantigens occurred in the cortex.
- Deletion induced by cognate self-peptides resulted in apoptosis in the cortex, medulla, or corticomedullary junction.
- Previous generalizations about negative selection sites were found to be over-simplified.
Conclusions:
- The site of negative selection is not exclusively the cortex or medulla.
- Apoptosis location during negative selection depends on the specific antigen encountered.
- Understanding these sites is crucial for T cell development and immune tolerance.