Abstract
The secreted form of the suppressor T cell factor specific for keyhole limpet hemocyanin derived from the hybridoma 34S-704 was found to consist of the two distinct polypeptide chains, i.e., the antigen-binding and the I-J-encoded chains. They were linked in covalent association with disulfide bonds. The two chains were cleaved by the reduction with dithiothreitol and were easy to reconstitute the active form of TsF. The association of the two distinct chains was suggested to be essential for the expression of the TsF activity.
Highlights
Our previous studies [6] have shown that the keyhole limpet hemocyanin (KLH)-TsF in the extracted or the secreted materials derived from the T cell hybridoma 34S-704 carries the antigenbinding moiety and the I-J-encoded determinants
The secreted TsF has different features from the extracted TsF, possessing the two characteristic determinants on the same molecule [7]. These data have indicated that the antigen-binding and the I-J-encoded polypeptide chains are noncovalently linked in cytoplasm or on the cell surface, and that they are secreted after their covalent association
The secreted TsF was examined to determine the presence of the interchain disulfide bonds and to cleave into the two polypeptide chains. 800/~1 of the ascites from the hybridoma 34S-704-bearing mice was applied to a KLH column
Summary
Fromthe Departmentof Immunology, Schoolof Medicine, Chiba University,Chiba,Japan. An antigen-specific suppression of antibody response has been known to be mediated by the factor (TsF) derived from suppressor T cells in a variety of experimental systems. The nature of the antigen-binding structure of TsF is still largely unknown, recent reports from various laboratories [8-11] have indicated that TsF carries the determinants analogous to the variable region of the immunoglobulin heavy chain. It is,'conceivable that at least two gene products are involved in the structural entity of an antigen-specific TsF: each product coded for by genes in one locus or the other. Our recent studies using the extracted TsF from a T cell hybrid specific for keyhole limpet hemocyanin (KLH) have strongly suggested that the TsF is composed of the two distinct polypeptide chains, i.e., the antigen-binding and the I-J-encoded chains in noncovalent association [7]. We show that the two dissociated polypeptide chains obtained after the reduction of the TsF with dithiothreitol (DTT) can successfully reassociate and reconstitute the TsF activity if the reduced TsF is not alkylated, and that the association of these two chains is essential for the expression of the TsF activity
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