Several different cell surface molecules control negative selection of medullary thymocytes

Area of Science:

• Immunology
• T cell biology
• Molecular immunology

Background:

• Negative selection is a critical process for maintaining immune tolerance.
• Previous research suggested negative selection might be controlled by a single molecule, but this has not been proven.
• The involvement of multiple cell surface molecules acting in concert is hypothesized.

Purpose of the Study:

• To investigate the role of cell surface molecules in Fas-independent negative selection.
• To determine if multiple molecules contribute to the costimulation required for negative selection.
• To explore the impact of cytokines on negative selection processes.

Main Methods:

• Analysis of heat-stable antigen (HSA)hiCD4+8- cells in the medulla.
• Investigating the contribution of CD28, CD5, and CD43 to Fas-independent negative selection.
• Utilizing cytokines IL-4 and IL-7 to block costimulatory functions in vivo.
• Comparing Fas-dependent and Fas-independent negative selection pathways.

Main Results:

• At least three cell surface molecules (CD28, CD5, CD43) contribute to Fas-independent negative selection.
• Cytokines IL-4 and IL-7 block the costimulatory function of these molecules.
• Coinjection of these cytokines with antigen in vivo abolishes Fas-independent negative selection.
• Fas-dependent negative selection remains functional despite cytokine treatment.

Conclusions:

• Efficient negative selection requires the coordinated function of multiple cell surface molecules.
• CD28, CD5, CD43, and Fas are essential for comprehensive negative selection.
• Cytokines can selectively modulate components of the negative selection pathway.