The T-cell repertoire is heavily influenced by tolerance to polymorphic self-antigens.

T cells with V beta 3+ alpha beta receptors are deleted by self-tolerance in mice with particular major histocompatibility complex/self-antigen combinations. This also occurs for other V beta elements. Polymorphism in the major histocompatibility complex and/or the self-antigens that cause massive deletion of T cells using particular V beta elements may be maintained by the need to balance the advantage of a diverse T-cell repertoire against the potential involvement of those elements in autoimmune disease.