The effect of mutant beta 2-microglobulins on the conformation of HLA-B27 detected by antibody and by CTL.
The arthritis-predisposing HLA-B27 consists of a heavy chain, a small peptide, and the monomorphic beta 2-microglobulin (beta 2-m). CTLs and a mAb, Ye-2, which recognize the complex with specificities both for the heavy chain and for the peptide, are available. The beta 2-m is in noncovalent association with the heavy chain at multiple points and is exchangeable with free beta 2-m outside of the complex. The purpose of our experiments was to test whether mutant beta 2-m capable of modulating HLA-B27 activity could be created. Eighteen recombinant mutants of the human beta 2-m were experimentally generated. In 14 of these, mutations were at or near residues that are either contact residues or interface residues with the heavy chain. Relative to the parent beta 2-m, two-thirds of the mutants showed reduced ability to exchange into HLA-B27 complexes. However, at least four of them induced more than 80% decrease in Ye-2 Ab reactivity. Two mutants were able to induce a minor decrease in susceptibility to lysis by four CTL clones. One of the CTL clones was autoreactive. Two of the CTL clones were specific for HLA-B27 cells experimentally infected with arthritis-causing Yersinia enterocolitica. These results indicate that certain beta 2-m residues play an indirect role in peptide presentation, although they are not directly associated with the peptide residues.
Fukazawa
T
T
Department of Medicine, University of California-Los Angeles 90024.
Hermann
E
E
Edidin
M
M
Wen
J
J
Huang
F
F
Kellner
H
H
Floege
J
J
Farahmandian
D
D
Williams
K M
KM
Yu
D T
DT
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D003602:Cytotoxicity, Immunologic; D017931:DNA Primers / Q000737:chemistry; D015796:HLA-B27 Antigen / Q000737:chemistry*; D006657:Histones / Q000737:chemistry / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000737:chemistry*
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D015796:HLA-B27 Antigen; D006657:Histones; D046911:Macromolecular Substances; D001613:beta 2-Microglobulin