CD8 independence and specificity of cytotoxic T lymphocytes restricted by HLA-Aw68.1.
The crystal structure of the HLA-Aw68.1 antigen binding site revealed a negatively charged pocket centred on aspartic acid 74 (Garrett et al. 1989). Access to this '74 pocket' is blocked in HLA-Aw68.2 and HLA-Aw69 by two substitutions at positions 97 and 116. This key feature suggests that the Aw68.1-peptide-specific interactions may involve salt bridges between oppositely charged residues. In this paper, the influenza epitope recognized by virus-specific HLA-Aw68.1-restricted cytotoxic T lymphocytes (CTL) has been defined in vitro with a synthetic peptide corresponding to residues 89-101 of the nucleoprotein (NP). Amino acid substitutions of the peptide NP 89-101 showed that the arginine at position 99 is an anchor point of the peptide within the Aw68.1 antigen binding site. Consistent with this we find that neither HLA-Aw68.2 nor HLA-Aw69 positive cells can present peptide NP 89-101 to Aw68.1-restricted CTL. Our results therefore suggest a model in which presentation of NP 89-101 by HLA-Aw68.1 is dependent upon interaction of the positively charged arginine residue at position 99 of the peptide, with the negatively charged aspartic acid in the '74 pocket' of HLA-Aw68.1. We also show that influenza-virus-specific HLA-Aw68.1-restricted CTL are CD8 independent. This result is consistent with the low affinity of HLA-Aw68.1 for CD8 (Salter et al. 1989) and reveals a unique example of CD8-independent priming of CTL by natural infection with a common pathogen in humans.
Cerundolo
V
V
Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, U.K.
Tse
A G
AG
Salter
R D
RD
Parham
P
P
Townsend
A
A
D000595:Amino Acid Sequence; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism*; D000956:Antigens, Viral / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D016827:CD8 Antigens; D000939:Epitopes / Q000737:chemistry / Q000378:metabolism; D015234:HLA-A Antigens / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D009980:Influenza A virus / Q000276:immunology; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000956:Antigens, Viral; D016827:CD8 Antigens; D000939:Epitopes; D015234:HLA-A Antigens; C053029:HLA-A*68 antigen; D010455:Peptides