Analysis of major histocompatibility complex class I-restricted hapten recognition by mutation of the V-J joining of T cell receptor alpha chains.
Hapten-specific T cell responses are responsible for chemically induced immune disorders. However, the molecular details of hapten interactions with T cell receptors (TCR) are poorly understood. Recent studies of trinitrophenyl (TNP)-specific responses revealed major histocompatibility complex-associated TNP-peptides as dominant epitopes for CD8+ and CD4+ T cells. The present study is based on the observation that two H-2Kb/TNP-specific CTL clones (II/7 and III/1), differing exclusively in two amino acids of their TCR alpha chains, also differed in their carrier specificities for various TNP-peptides. The genes of the two alpha chains and the common beta chain were cloned into expression vectors. Transfection of the TCR alpha chain of clone III/1 into a hybridoma of clone II/7 also transferred the fine specificity of clone III/1, indicating that the small alpha chain variations were indeed responsible for the different carrier specificities. Point mutations bridging the difference between the alpha chains of clones II/7 and III/1 and functional studies of the respective TCR alpha beta transfectants into a TCR-negative hybridoma revealed an unexpected result: the two receptors did not represent examples of structural complementarity for different sets of hapten-peptide conjugates; rather, they resembled two structures of principally similar specificity but of significantly different overall affinity. This was demonstrated more directly by comparing the fine specificities of III/1 transfectants expressing or not expressing the co-receptor CD8: the CD8-negative III/1 transfectant assumed a specificity pattern indistinguishable from that of a CD8-expressing, II/7-derived transfectant. Hence, comparable alterations of antigen recognition may be induced either by subtle TCR alterations or by removal of CD8, i.e. by the presence or absence of a non-polymorphic adhesion molecule.
von Bonin
A
A
Max-Planck-Institut für Immunbiologie, Freiburg, Germany.
Plaga
S
S
Ruh
H
H
Hebbelmann
S
S
Pflugfelder
U
U
Martin
S
S
Weltzien
H U
HU
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D001483:Base Sequence; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D000939:Epitopes / Q000235:genetics; D006183:H-2 Antigens / Q000235:genetics* / Q000276:immunology; D006241:Haptens / Q000235:genetics* / Q000276:immunology; D006825:Hybridomas; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics* / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014162:Transfection / Q000276:immunology
D000939:Epitopes; D006183:H-2 Antigens; C032876:H-2Kb protein, mouse; D006241:Haptens; D016693:Receptors, Antigen, T-Cell, alpha-beta