T cell-recognized antigenic peptides derived from the cellular genome are not protein degradation products but can be generated directly by transcription and translation of short subgenic regions. A hypothesis.

It is now widely accepted that cytolytic T cells recognize their antigens in the form of small peptides bound to major histocompatibility complex molecules at the surface of the target cells. We present here the hypothesis that, when these antigenic peptides are derived from the cellular genome, they are not degradation products of cellular proteins but can be generated directly by the autonomous transcription and translation of short subgenic regions that we propose to name "peptons". We discuss some consequences of the notion that antigenic peptides can be produced in the absence of synthesis of messenger RNA and protein from the corresponding genes.