Contemporary models for peripheral tolerance and the classical 'historical postulate'

The formulators of Clonal Selection Theory proposed that what distinguishes self from foreign antigens is their early appearance in development, and their continuous presence thereafter. This early presence of a self antigen in an animals life history was envisaged to ensure that lymphocytes specific for the self antigen were silenced rather than activated. I call this idea 'the historical postulate'. Contemporary models for the activation/inactivation of helper T cells implicitly violate this postulate. I argue against such a violation and for a model of T helper cell activation/inactivation that reconciles contemporary observations with the postulate.