INTERLEUKIN-7-INDUCED EXPRESSION OF SPECIFIC T-CELL RECEPTOR-GAMMA VARIABLE REGION GENES IN MURINE FETAL LIVER CULTURES

We previously reported that culture of murine fetal liver (FL) cells w ith interleukin 7 (IL-7) results in expression of high levels of T cel l receptor (TCR) gamma transcripts by a population of cells expressing Thy-1 and Pgp-1, suggesting that IL-7 promotes the growth and/or diff erentiation of pre-T cells. We demonstrate herein that culture of FL c ells for 7 d with IL-7 caused the rearrangement and expression of TCR, gamma variable (V) region genes Vgamma4 and Vgamma6, but not Vgamma5 or Vgamma7. Since this effect was not blocked by- hydroxyurea, it appe ared to represent induction of expression of these genes by IL-7 rathe r than expansion of a preexisting positive population. We also show th at IL-7 induced RAG-1 and RAG-2 mRNA expression by FL cells. These dat a provide evidence that specific TCR gamma/delta V region genes can be rearranged and expressed by T lineage cells before their migration to the thymus, in response to IL-7.