Preferential expression of a defined T-cell receptor β-chain gene in hapten-specific cytotoxic T-cell clones

Abstract

A multitude of different antigens can be recognized by T cells through specific receptors. Both the α- and β-chains of the T-cell receptor contribute to the antigen recognition portion¹. The repertoire of β-chain variable region (V_β) gene segments is limited to some 20 elements^2–4 which seem to be used randomly in different T cells^2,5,6. Diversity at the β-chain level can be created in several ways^2,3,7–12: a multiplicity of germline gene segments; combinatorial diversity by rearranging different V, diversity (D), joining (J) and constant (C) region elements; junctional diversity by joining gene segments at different sites; N-region diversity, that is, insertion of random nucleotides at junctional sites; and somatic mutation¹³. However, the major sources and the extent of diversity of the T-cell receptor are unclear. To address this issue, 42 H–2K^b-restricted, 2,4,6-trinitrophenyl (TNP)-specific cytotoxic T-cell (T_c) clones from C57BL/6 mice were characterized with respect to expression of different β-chain gene segments in messenger RNA using specific oligonucleotide probes. We report here that nearly half of the T_c clones use identical elements for productive β-chain gene rearrangement. Thus, there is a restriction in the use of β-chain gene segments in this panel of T_c clones which favours a particular V_β–D_β–J_β–C_β combination with a defined D_β element.