The LH8-105 T cell clone, obtained by radiation leukemia virus-induced transformation of hen egg-white lysozyme (HEL)-specific mouse suppressor T lymphocytes, constitutively releases in the culture supernatant products able to induce specific suppression of the immune response to HEL. LH8-105 cells rearrange and express the genes encoding the alpha and beta chains of the antigen-specific T cell receptor and display membrane T cell receptor structures. LH8-105 mRNA specific for the alpha and beta chains of the T cell receptor were positively selected on filter-bound cDNA encoding constant regions of alpha and beta chains, eluted and translated into Xenopus laevis oocytes. Translation products were then tested in vivo for specific suppression of the anti-HEL antibody response. LH8-105 culture supernatant and translation products of LH8-105 poly(A)+ RNA or a mixture of alpha and beta chain-homologous mRNA induce HEL-specific suppression whereas translation products of LH8-105 mRNA eluted from irrelevant DNA or unrecombined mRNA eluted from alpha and beta cDNA do not exert suppressive activity. These results indicate that alpha and beta chain-homologous mRNA expressed in LH8-105 cells direct the synthesis of molecules able to induce HEL-specific suppression.