Synthesis of biologically active fibroblast-activating factor (FAF) by Xenopus oocytes injected with T lymphocyte mRNA

Abstract

Activation of human peripheral blood T lymphocytes results in the production of fibroblast-activating factor (FAF), a mediator which stimulates fibroblast proliferation. This lymphokine, which may provide a molecular link between cell-mediated immune reactions and fibroplasia, has been identified as a T-cell product both in vitro and in vivo. In order to study the mechanisms of synthesis and activity of FAF, poly(A) RNA was isolated from concanavalin A-stimulated T lymphocytes and injected into Xenopus oocytes. The injected oocytes translated the messenger RNA and produced a material with the biological and biochemical properties of human FAF. The oocyte product induced proliferation in serum-free quiescent fibroblast monolayers and exhibited the same molecular weight and charge as the T-cell-derived factor. Oocytes injected with poly(A)-RNA from unstimulated T lymphocytes produced little, if any, FAF activity. We conclude that activation of T lymphocytes enhances transcription of FAF mRNA as detected in the oocyte translation assay. This translated material has biological activity and biochemical characteristics consistent with FAF and is suitable for further studies on the expression and synthesis of FAF (poly)peptides.