We have analyzed the genetic basis for T cell recognition of an endogenous major histocompatibility complex class II-restricted self peptide. Transgenic mice expressing the influenza virus PR8 hemagglutinin I-Ed-restricted determinant $1 (HA Tg mice) mediate negative selection ofPR8 Sl-specific T cells, but respond to immunization with a virus containing a closely related analogue, $1(Kl13). Se...
