Functional significance of varied quantitative and qualitative expression of HLA-A2.1 antigens in determining the susceptibility of cells to cytotoxic T lymphocytes.
To determine whether varied quantitative HLA expression affects the susceptibility of target cells to CTLs, a panel of 15 EBV-transformed lymphoblastoid cell lines expressing a fivefold difference of surface HLA-A2.1 antigens were employed. The susceptibility of these cell lines to HLA-A2.1-restricted and influenza virus matrix peptide-specific CTLs was correlated with the amounts of HLA-A2.1 antigens expressed on their surface. The results show a linear correlation between both parameters using exogenous viral peptide. The same linear correlation was observed when target cells infected with influenza virus were studied. These findings support the hypothesis that the amount of HLA antigens expressed on the cell surface is functionally significant in determining the susceptibility of target cells to CTLs. During our study, we also found that two HLA-A-2.1-positive cell lines were unresponsive to the CTL. Further investigation of the amino acid sequences of these cell lines reveals that their HLA-A2.1 antigens belong to the HLA-A0207 subtype which is different from HLA-A0201(A2.1) by one nucleotide. This difference results in an amino acid substitution from tyrosine to cysteine at position 99 of HLA-A2.1 heavy chains. Using a peptide-induced reconstitution assay, it was shown that failure of the peptide binding is responsible for the absence of cytotoxicity. This finding supports the hypothesis that amino acid 99 plays an important role in determining the peptide-binding specificity of HLA-A2 molecules.
Shieh
D C
DC
Department of Pathology and Laboratory Medicine, University of Florida, Gainesville, USA.
Gammon
M C
MC
Zweerink
H J
HJ
Kao
K J
KJ
D001665:Binding Sites; D002461:Cell Line, Transformed; D003602:Cytotoxicity, Immunologic; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D015789:HLA-A2 Antigen / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D004854:Herpesvirus 4, Human; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D011485:Protein Binding; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014763:Viral Matrix Proteins / Q000276:immunology
D018076:DNA, Complementary; D015789:HLA-A2 Antigen; C031540:M-protein, influenza virus; D010446:Peptide Fragments; D014763:Viral Matrix Proteins