Dissection of CD8+ T cell immunodominance hierarchy in human influenza virus infection

Abstract

Abstract Based on magnitude, virus-specific CD8+ cytotoxic T lymphocyte (CTL) responses can be grouped as immunodominant and subdominant. Such immunodominance hierarchies are governed by multiple factors, including naïve T cell precursor frequency, proliferative capacity and clonotypic diversity of Ag-specific CTLs. However, how these factors determine together inter/intra-individual immunodominance remains elusive. In this study, we dissected CTL immunodominance hierarchy for universally conserved influenza (IAV)-specific epitopes. Our data from 59 donors covering the HLAI types presenting universally conserved IAV-specific peptides, HLA-A* 0201, A*0301, B*2705, B*5701, B*1801 and B*0801, revealed that CTLs directed against HLA-A* 0201:M158 were immunodominant, except in A*0201+B*2705+ heterozygous individuals, where the HLA-B* 2705-NP383 recalls higher magnitude CTL responses. Subsequently, we further dissected the basis of B*2705 immundomination over A*0201 by analyses of T cell Receptor (TCRαβ) repertoire, TCR avidity and kinetics of killing and proliferation. Our data show that following in vitro peptide stimulation, B*2705:NP383 CTLs proliferate rapidly acquiring higher levels of polyfunctionality than A*02:M158 specific CTLs. Furthermore, ex vivo single-cell paired CDR3αβ analysis revealed that public A*0201:M158 TCRs characterized by Vβ19/Vα27 profiles in A*0201 individuals are significantly reduced/absent in A*0201+B*2705+ individuals. Clonal analysis of M158 dominant public TCRs suggested B*2705-mediated removal of self-reactive TCRs and is under investigation. Our study provides insights into the importance of human IAV-specific immunodominance at quantitative and qualitative levels.