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→Cell death
Anergy is easily induced in T cells ''in vivo'' by activation of T cell receptors without co-stimulation; it can be induced ''in vitro'' by the injection of potent superantigens (antigens that stimulate T cells with different receptor types, using the same T cell receptor V gene). Anergy occurs naturally when there is a downregulation of T cell receptors as a result of chronic stimulation. Anergy induced without co-stimulation can be reversed by IL-2.
Anergy is easily induced in T cells ''in vivo'' by activation of T cell receptors without co-stimulation; it can be induced ''in vitro'' by the injection of potent superantigens (antigens that stimulate T cells with different receptor types, using the same T cell receptor V gene). Anergy occurs naturally when there is a downregulation of T cell receptors as a result of chronic stimulation. Anergy induced without co-stimulation can be reversed by IL-2.
'''Cell death'''; Peripheral deletion of T cells requires the engagement of Fas by Fas ligand.
Peripheral deletion of T cells requires the engagement of:
Deficiencies in Fas ligand lead to lymphoproliferative disorders. After activation by an antigen, T cells upregulate expression of Fas ligand - some tissues, such as the testis and retina, constitutively express Fas ligand to protect themselves from activated T cells
Cell death is also induced by TNF via the TNF receptor; CTLA-4 has recently also been implicated in cell death. The subsequent signalling cascade activates proteases, such as IL-1beta Converting Enzyme (ICE), that leads to cell apoptosis.
===Immune deviation===
===Immune deviation===