Constant region determinants on the antigen-binding chain of the suppressor T-cell factor

Abstract

Antigen recognition units on T cells, including isolated antigen receptors and antigen-specific T-cell factors, have been found to have antigen-binding moieties like conventional immunoglobulins and to carry the determinants analogous to the variable (V) region of the immunoglobulin^1–5. However, the immunoglobulin heavy chain constant region (Igh-C) determinants have not been demonstrated on T-cell receptor molecules^6–9. If they possess unique constant region determinants, they must therefore be entirely distinct from the Igh-C. By production of an antiserum between Igh allotype congeneic mice Owen et al. suggest that a T-cell constant region determinant (Tsu^d) is encoded by a gene located near the Igh-C genes on the 12th chromosome^10,11. In addition, we have also demonstrated that a BALB/c anti-CB-20 antiserum detects at least two distinct allotypic determinants, either of which is expressed on the antigen-specific suppressor or augmenting T-cell factor¹². We now demonstrate that the new allotypic determinants detected by the BALB/c anti-CB-20 antiserum are expressed on the constant region of the antigen-binding molecule of an antigen-specific suppressor T-cell factor (TsF), and that this molecule is encoded by genes located on the right side of the Igh- V gene locus on the 12th chromosome.