title: A recombinant single-chain HLA-A2.1 molecule, with a cis active beta-2-microglobulin domain, is biologically active in peptide binding and antigen presentation.
abstract: We have constructed a recombinant single-chain human HLA-A2.1 molecule (from A*0201) with a covalently attached beta 2m. This molecule (MSC beta A2.1) can be detected on the surface of transfected beta 2m- human cells by conformational antibodies W6/32 and BB7.2 and by anti-human beta 2m mAb BM-63. The covalent beta 2m, now a domain of the MSC beta A2.1 molecule, does not rescue endogenous Class I surface expression. Instead, it works in cis to achieve correct folding of the single-chain molecule. Immunoprecipitation shows that MSC beta A2.1 is a 60-kDa molecule with no dissociable beta 2m. The half-life of the MSC beta A2.1 molecule on transfected cell surfaces was as long as that of two-chain HLA-A2.1 molecules. The MSC beta A2.1 molecule was active in presentation of HTLV-I Tax 11-19 peptide and an endogenous peptide to specific CTL. MSC beta A2.1 molecules and wild-type HLA-A2.1 molecules on live cells can bind the HBV core peptide 18-27 with comparable affinities. These results show that MSC beta A2.1 molecules retain the functional ability to present both pulsed and endogenous antigens to the appropriate T cells, and thus may be useful components of antiviral vaccines.
authors.affiliation: Laboratory of Biochemistry, National Cancer Institute, NIH, Bethesda, MD, USA.
authors.forename: L
authors.initials: L
authors.lastname: Lee
authors.forename: D
authors.initials: D
authors.lastname: Loftus
authors.forename: E
authors.initials: E
authors.lastname: Appella
authors.forename: D H
authors.initials: DH
authors.lastname: Margulies
authors.forename: M
authors.initials: M
authors.lastname: Mage
mesh_terms: D017951:Antigen Presentation / Q000187:drug effects*; D015789:HLA-A2 Antigen / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D001613:beta 2-Microglobulin / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*
chemical_list: D015789:HLA-A2 Antigen; D011994:Recombinant Proteins; D001613:beta 2-Microglobulin