Negative selection, not receptor editing, is a physiological response of autoreactive thymocytes

Area of Science:

• Immunology
• Cellular and Molecular Immunology
• T cell biology

Background:

• Antigen receptor editing, a secondary rearrangement of antigen receptor genes, is a key tolerance mechanism in B cells.
• The role and existence of antigen receptor editing in T cells remain controversial and poorly understood.

Purpose of the Study:

• To investigate the phenomenon of T cell receptor (TCR) editing in T cells.
• To clarify the role of TCR editing as a tolerance mechanism in T cell development.

Main Methods:

• Utilized a novel Tcra knock-in locus to ensure proper timing of TCRα expression and enable secondary rearrangements.
• Studied T cell responses to self-antigen in the context of engineered TCRα expression.

Main Results:

• Negative selection of CD4/CD8 double positive thymocytes was the only identifiable response to self-antigen.
• No evidence supporting antigen-induced TCR editing was observed.
• TCRα chain replacement by ongoing gene rearrangement occurred in some T cells, independent of self-antigen presence.

Conclusions:

• Antigen-induced TCR editing does not appear to be a significant mechanism for T cell tolerance.
• TCR gene rearrangement can occur independently of antigen stimulation during T cell development.