The hapten/class I MHC-specific soluble immunoregulatory molecules produced by CD8+T cells from dinitrobenzene sulfonate-primed mice express the binding specificity and serologic determinants of alpha/beta TCR. To examine the genes used to encode these soluble immunoregulatory molecules, we utilized a surface TCR expressing Ts hybridoma, which constitutively produces a DNP/Kd-specific regulatory molecule. Northern and Southern analyses indicated that MTs 79.1 cells use a V beta 8 and a V alpha 4 gene to encode the variable regions of the surface alpha/beta TCR. A panel of TCR- variants was generated by subjecting MTs 79.1 cells to gamma-irradiation. Twelve of the TCR- variants were chosen for detailed characterization. Northern blot analyses indicated the absence of the MTs 79.1 V alpha 4 chain transcript in five of the variants and the absence of the parental V beta 8 chain transcript in the other seven. Southern blot analyses demonstrated the deletion of the parental gene encoding the alpha- or beta-chain from the genome of the respective mutant. None of the 12 TCR gene deletion mutants produced the parental suppressive activity. Expression of the parental TCR beta-chain gene in one of the beta-chain gene deletion mutants reconstituted the ability to produce this activity. As with the MTs 79.1 molecule, the regulatory molecule produced by the beta-chain gene transfectant was bound by and eluted from Sepharose columns coupled with either DNP or anti-V beta 8 antibodies. These results establish a strong linkage between the suppressor molecules produced by these Ts and TCR alpha- and beta-chain gene transcription.