Human leukocyte antigens A*3001 and A*3002 show distinct peptide-binding Patterns of the Mycobacterium tuberculosis protein TB10.4 : consequences for immune recognition

摘要

High-tuberculosis (TB)-burden countries are located in sub-Saharan Africa. We examined the frequencyof human leukocyte antigen (HLA) alleles, followed by recombinant expression of the most frequentHLA-A alleles, i.e., HLA-A*3001 and HLA-A*3002, to study differences in mycobacterial peptide presentationand CD8 T-cell recognition. We screened a peptide library (9-mer peptides with an 8-amino-acidoverlap) for binding, affinity, and off-rate of the Mycobacterium tuberculosis-associated antigen TB10.4 andidentified only three TB10.4 peptides with considerable binding to HLA-A*3001. In contrast, 22 peptidesbound to HLA-A*3002. This reflects a marked difference in the binding preference between the two alleles,with A*3002 tolerating a more promiscuous peptide-binding pattern and A*3001 accommodating only avery selective peptide repertoire. Subsequent analysis of the affinity and off-rate of the binding peptidesrevealed a strong affinity (8 nM to 7 M) and moderate off-rate (20 min to 3 h) for both alleles.Construction of HLA-A*3001 and HLA-A*3002 tetramers containing selected binding peptides fromTB10.4, including a peptide which was shared among both alleles, QIMYNYPAM (TB10.43–11), allowed usto enumerate epitope-specific T cells in HLA-A*3001- and HLA-A*3002-typed patients with active TB.HLA-A*3001 and HLA-A*3002 major histocompatibility complex-peptide complexes were recognized inindividuals with active TB, irrespective of their homozygous HLA-A*3001 or HLA-A*3002 genetic background.The antigen-specific T cells exhibited the CD45RA CCR7 precursor phenotype and the interleukin-7 receptor (CD127), which were different from the phenotype and receptor exhibited by the parentalCD8 T-cell population.