INTERLEUKIN-7 - A COFACTOR FOR V(D)J REARRANGEMENT OF THE T-CELL RECEPTOR BETA-GENE

The diversity of the T cell receptor repertoire is generated by rearra ngement of gene elements in immature thymocytes. To identify a thymic signal that induces this rearrangement, a variety of agents were teste d for their ability to induce rearrangement of the T cell receptor bet a gene in suspensions of thymocytes from mouse embryos at day 14 of ge station. Of 16 agents tested, only interleukin-7 (IL-7) induced V(D)J gene rearrangement and sustained expression of the RAG-1 and RAG-2 gen es, which are known to control rearrangement. These data implicate IL- 7, a cytokine that is abundantly expressed in embryonic thymus, in dri ving gene rearrangement during early T cell development.