Binding of TCR multimers and a TCR-like antibody with distinct fine-specificities is dependent on the surface density of HLA complexes

• Published in: PloS one 2012-12, Vol.7 (12), p.e51397-e51397
• Main Authors: Low, Jianrong L, Naidoo, Anneta, Yeo, Gladys, Gehring, Adam J, Ho, Zi Zong, Yau, Yin Hoe, Shochat, Susana G, Kranz, David M, Bertoletti, Antonio, Grotenbreg, Gijsbert M
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Antigen presentation; Antigenic determinants; Antigens; Autoantibodies - immunology; Avidity; Beads; Binding; Biochemistry; Biodegradation; Biology; CD8 antigen; Cell Line; Cloning; Cloning, Molecular; Cytometry; Density; Drug delivery; Drug delivery systems; Drugs; Epitopes; Flow Cytometry; Genetic transformation; Genotypes; Hepatitis; Hepatitis B; Hepatitis B virus; Hepatocytes; Histocompatibility antigen HLA; HLA antigens; HLA Antigens - immunology; HLA Antigens - metabolism; Humans; Immunogenicity; Immunoglobulins; Immunology; Immunosuppressive agents; Immunosurveillance; Infections; Limit of Detection; Lymphocytes; Lymphocytes T; Major histocompatibility complex; Medicine; Monoclonal antibodies; Mutation; Peptides; Receptors, Antigen, T-Cell - genetics; Receptors, Antigen, T-Cell - immunology; Receptors, Antigen, T-Cell - metabolism; Scaffolds; Science; Sequence Homology, Amino Acid; Streptavidin; Surface Plasmon Resonance; T cell receptors; T cells; T-cell receptor; Transformation; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0051397

Class I Major Histocompatibility Complex (MHC) molecules evolved to sample degraded protein fragments from the interior of the cell, and to display them at the surface for immune surveillance by CD8(+) T cells. The ability of these lymphocytes to identify immunogenic peptide-MHC (pMHC) products on, for example, infected hepatocytes, and to subsequently eliminate those cells, is crucial for the control of hepatitis B virus (HBV). Various protein scaffolds have been designed to recapitulate the specific recognition of presented antigens with the aim to be exploited both diagnostically (e.g. to visualize cells exposed to infectious agents or cellular transformation) and therapeutically (e.g. for the delivery of drugs to compromised cells). In line with this, we report the construction of a soluble tetrameric form of an αβ T cell receptor (TCR) specific for the HBV epitope Env(183-191) restricted by HLA-A*02:01, and compare its avidity and fine-specificity with a TCR-like monoclonal antibody generated against the same HLA target. A flow cytometry-based assay with streptavidin-coated beads loaded with Env(183-191)/HLA-A*02:01 complexes at high surface density, enabled us to probe the specific interaction of these molecules with their cognate pMHC. We demonstrate that the TCR tetramer has similar avidity for the pMHC as the antibody, but they differ in their fine-specificity, with only the TCR tetramer being capable of binding both natural variants of the Env(183-191) epitope found in HBV genotypes A/C/D (187Arg) and genotype B (187Lys). Collectively, the results highlight the promiscuity of our soluble TCR, which could be an advantageous feature when targeting cells infected with a mutation-prone virus, but that binding of the soluble oligomeric TCR relies considerably on the surface density of the presented antigen.