Aleatory Epitope Recognition Prevails in Human T Cell Responses?

Abstract

Eli Sercarz pioneered epitope recognition by T cells. Studying mice, he made the seminal observation decades ago that epitope dominance is so unpredictable with mixed MHC haplotypes that he coined it aleatory, for dice-like. Accordingly, for every individual there is a unique potential epitope space that is defined by the polymorphic and polygenic MHC molecules (restriction elements) expressed. Of this potential epitope space, some peptides will elicit stronger T cell responses than others, bringing about the actually realized epitope space. The selection of the actually recognized peptides from the potential epitope space is random, however, resulting in unique epitope dominance and hierarchy patterns in individuals. Engaging in brute-force epitope scans, which permit the assessment of the entire potential epitope space at the highest possible resolution, we observe aleatory epitope recognition in human CD8 cell responses to viruses. Because the selection of peptide has fundamental implications for successful T cell immune monitoring, we dedicate this article to Eli Sercarz in a special issue of Critical Reviews™ in Immunology in his honor.