Allele-unrestricted presentation of lidocaine by HLA-DR molecules to specific αβ F T cell clones

T cells recognize peptide and non-peptide antigens. Drugs represent typical examples of nonpeptide antigens. The majority of drug-specific T cells are αβF TCR T cells and are MHC class I or II restricted. Here we show the existence of drug (lidocaine)-specific T cell clones which proliferate in the presence of antigen-presenting cells (APC) with different HLA alleles. Two clones (SFT24 and E20) were analyzed in detail. They show a narrow dose-dependent proliferation to lidocaine, but not to procaine. With the use of a panel of HLA-typed allogeneic APC, we observed that certain allogeneic APC plus lidocaine lead to a similar, others to partial and some to no proliferation of the lidocaine-specific T cell clones. An APC-independent proliferation could be excluded since both clones proliferated only marginally without APC and increasing the number of APC resulted in a higher proliferation. Blocking experiments with anti-DP, -DQ and -DR antibodies showed that lidocaine is presented in a HLA-DR-restricted way both with autologous or allogeneic APC. Mouse fibroblasts transfected with an allogeneic HLA-DRB1*01 but not HLA-DR-negative mouse fibroblasts could serve as presenting cells. Fixation of APC did not hamper drug presentation, but pulsing of APC with the drug was not possible, indicating that processing is not required and that lidocaine binds in an unstable way to the MHC–peptide complex. This degenerate drug recognition has certain features of superantigen recognition, such as the ability of drugs to bind from the outside to multiple HLA-DR alleles. Such features of drug recognition may open new therapeutic possibilities to intervene with TCR–MHC interactions in a selective way.