Negative selection of developing T cells is an important mechanism for maintaining self-tolerance in the immune system. During this process, which occurs in the thymus, developing T cells that react strongly against self-antigens are eliminated in order to prevent autoimmune responses.

During negative selection, developing T cells encounter a diverse array of self-antigens presented by antigen-presenting cells within the thymus. T cells with T cell receptors (TCRs) that exhibit high affinity for self-antigens undergo apoptosis or programmed cell death. By removing T cells with strong self-reactivity, negative selection ensures that only healthy, normal cells enter the peripheral immune system. This mechanism promotes self-tolerance, which prevents the immune system from attacking the body's own cells and tissues.