Antigen contacts by Ni-reactive TCR: typical αβ chain cooperation versus α chain-dominated specificity

Abstract

VB17(+) TCR dominate in Ni-driven T cell cultures from highly Ni-sensitized patients. Using transfection of TCR from three CD4(+), VB17(+), Ni-specific human T cell clones, we studied their Ni-MHC contacts by site-directed TCR mutation and combination of alpha and ss chains between different TCR. All three TCR exhibited N-nucleotide-determined Arg-Asp motifs in their CDR3-ss sequences. Two of them were specifically restricted to HLA-DR13, while the third one accepted a variety of HLA-DR alleles. The highly similar alpha or ss chains of the DR13-restricted TCR were interchangable without loss of specificity, but alpha or ss chains of other TCR were not tolerated. Mutations of their Arg-Asp motif revealed loss of reactivity upon exchanging Asp for Glu or Ala and of Arg for Ala but not of Arg for Lys or the Ni binding His. Reactivity was also destroyed by mutation of alpha chain position 51, proposed as a general contact site for MHC. Hence, in these two TCR the Arg-Asp motif is clearly involved in contacting Ni-MHC complexes, and close cooperation between alpha and ss chain is required. In contrast, the third TCR retained Ni reactivity upon mutation of alpha chain position 51 or of its ss chain Arg-Asp motif, which rather affected the pattern of DR cross-restriction. Moreover, its alpha chain paired with various ss chains from other, even mouse TCR, irrespective of their specificity, retaining Ni reactivity as well as promiscuous HLA-DR restriction. This preponderance of an alpha chain in defining specificity indicates fundamental differences in Ni interactions of individual TCR and implies that ss chain similarities may not necessarily result from antigen selection.

Characterization of Drug-Specific T Cells in Phenobarbital- Induced Eruption

“…Allele-unrestricted presentation of haptenic small compounds by MHC class II molecules is recently described in the interactions between T cells specific for lidocaine, sulfamethoxazole, and amoxicillin and APC (16,27). Direct binding of nickel to particular amino acids of cryptic MHC peptides results in conformational change of the MHC-peptide-metal complex so as to be recognized by nickel-specific T cells irrespective of APC alleles (28). Furthermore, a monomorphic surface molecule, CD39, can function as additional recognition structures on haptenated target cells for HLA-A1-restricted hapten-specific CD8 ϩ T cells (29).…”

T-cell receptor (TCR) interaction with peptides that mimic nickel offers insight into nickel contact allergy

“…In the structure of the complex, these amino acids are not only in extensive contact with the critical pHIR amino acids p5I, p7K, and p8R, as mentioned above, but they also interact with the adjacent DR52c α1 and β1 helices (Table 1). In a previous study of another Ni ++ -reactive TCR whose Vα and Vβ CDRs were nearly identical to those of ANi2.3 and that also had RDGY at the tip of Vβ CDR3, mutation of the D to A was also shown to eliminate the Ni ++ response, but so did the very conservative mutation of D to E (25,26). Therefore, we also assessed the effect of this Vβ D95-to-E mutation on the ANi2.3 T cell (Fig.…”

Metal-Protein Complex-Mediated Transport and Delivery of Ni2+ to TCR/MHC Contact Sites in Nickel-Specific Human T Cell Activation

“…They were cultured in RPMI-HS with 1 g/ml PHA-P (Murex Diagnostics, Dartford, U.K.) and 100 IU/ml recombinant human IL-2 (Proleukin; EuroCetus, Ratingen, Germany) on irradiated, allogeneic PBMC. Clones with prefix ANi (synonymous with HSA.Ni) from donor IF have been described before (5) as well as clone SE9 of donor SE (22). Clones of donor KG with prefix BC or SDC were newly prepared from PBMC or skin lesions, respectively.…”