Disulfide-linked surface molecules of monoclonal antigen-specific suppressor T cells: evidence for T cell receptor structures.

By two-dimensional polyacrylamide gel electrophoresis analysis under nonreducing/reducing conditions, five proteins with interchain disulfide bridges are revealed on the surface of the suppressor T cell lymphoma line LH8-105 obtained by radiation leukemia virus-induced transformation of hen egg-white lysozyme-specific suppressor T lymphocytes. Two disulfide-linked surface proteins expressed by LH8-105 cells have been positively identified by immunoprecipitation with specific antisera. The major labeled membrane protein of LH8-105 cells is the murine leukemia virus env glycoprotein gp70. The second disulfide-linked molecule identified on LH8-105 cells has a molecular mass of 84 kDa under nonreducing conditions and 42 kDa after reduction, and is immunoprecipitated by an antiserum which recognizes the T cell receptor for antigen. A disulfide-linked molecule of a similar molecular mass is also immunoprecipitated from surface-labeled LH8-105 cells by a rabbit antiserum directed against a synthetic peptide predicted from the nucleotide sequence of a cDNA clone encoding the beta chain constant region of a helper T cell hybridoma. Therefore, a dimeric structure comparable to the T cell receptor expressed by cytotoxic and helper T cells is present on the cell surface of these monoclonal antigen-specific suppressor T cells.