Regeneration and tolerance factor of the human placenta induces IL-10 production

Regeneration and tolerance factor (RTF) was originally identified in the placenta of mice and the isolated protein shown to have suppressive effects. In these studies, the gene cloned from thymus tissue was mapped to human chromosome 12. The role of recombinant RTF on cytokines was examined. In addition, we examined the human placenta by immunohistochemistry for RTF expression. RTF was expressed at the peripheral layer of cytotrophoblast in 7-9-week-old placentas. Using the RTF gene sequence, a recombinant protein was prepared and shown to induce IL-10 production. These data indicate that RTF is expressed by the tissues most intimately involved at the maternal-fetal interface, and its biological activity is capable of producing the necessary immune response for initiating and maintaining the maternal-fetal relationship.