Production of transforming growth factor beta by human peripheral blood monocytes and neutrophils.

Human peripheral blood monocytes and neutrophils secrete TGF-beta. Activation of monocytes with LPS stimulates the secretion of TGF-beta; however, the production of TGF-beta by neutrophils was not altered by treatment with LPS. The secreted TGF-beta appears to be in a fully active form since acid treatment of the conditioned medium does not increase the amount of TGF-beta activity. TGF-beta 1 transcripts were detected at similar levels in both activated and nonactivated monocytes and neutrophils, suggesting that the increase in TGF-beta secretion after activation of monocytes is regulated by a posttranscriptional mechanism. Western blot analysis with anti-N-terminal TGF-beta 1 peptide antibodies indicate the leukocyte-derived TGF-beta is beta 1. In addition, TGF-beta 1 transcripts were detected in rat peritoneal macrophages and in a differentiating human hematopoietic tumor cell line (HEL). The ability of inflammatory cells such as monocytes and neutrophils to produce TGF-beta may play an important role in the function of these cells in wound repair, in the immune response, and in the pathogenesis of fibrotic diseases.