Modulation of fibroblast growth by a lymphokine of human T cell continuous T cell line origin.

Human peripheral blood T lymphocytes activated by mitogens or specific antigen produce a mediator that stimulates proliferation in a quiescent population of dermal fibroblasts. This lymphocyte product, which may have implications in the fibrosis associated with chronic cell-mediated inflammatory lesions, is not elaborated by unstimulated lymphocytes. Characterization of the fibroblast mitogenic factor differentiated it from a monocyte-derived factor with similar activity. The T cell factor appears to be a protein with an apparent m.w. of 40,000 and an isoelectric point between 5.0 and 5.5. This fibroblast growth factor can be produced in the relative absence of monocytes, and further evidence that the factor is a T cell product stems from the ability of a human T cell line to generate such a factor. Comparison of the biochemical characteristics of the normal T cell product with those of the T cell line revealed them to be indistinguishable. Thus, the T cell line can be used as a source of fibroblast-activating factor (FAF) for more detailed analysis of its structure and function. Further characterization of this lymphokine may contribute to understanding the mechanisms that mediate fibrosis in normal tissue repair as well as in the pathophysiologic fibrotic response associated with certain chronic inflammatory diseases.