title: Transforming growth factor-beta is a potent immunosuppressive agent that inhibits IL-1-dependent lymphocyte proliferation.
abstract: Transforming growth factor-beta (TGF-beta), a product of neoplastic and hemopoietic cells, is a bifunctional regulator of the immune response. At femtomolar concentrations, TGF-beta stimulates monocyte migration, and picomolar quantities induce synthesis of monocyte growth factors, including IL-1, that may promote tissue repair by regulating fibrosis and angiogenesis. Paradoxically, TGF-beta at picomolar concentrations also blocks the ability of IL-1 to stimulate lymphocyte proliferation. At 0.01 to 1.0 ng/ml, TGF-beta 1 and its homologue, TGF-beta 2, suppress the IL-1-dependent murine thymocyte proliferation assay. TGF-beta also inhibits human peripheral blood T lymphocyte mitogenesis. Inhibition of cell division appears to occur after activation of the lymphocytes inasmuch as neither gene expression nor translation of IL-2R is suppressed. Furthermore, TGF-beta does not block synthesis of IL-2. Therefore, TGF-beta 1 and TGF-beta 2 likely act at a site distal to IL-1 to block lymphocyte DNA synthesis. These findings suggest that TGF-beta secreted in an inflammatory site may be beneficial in diminishing lymphocyte function while promoting fibrosis and tissue repair. However, TGF-beta generated by neoplastic tissues may provide a mechanism for unrestricted tumor cell growth through its selective immunosuppressive effects.
mesh_terms: D006801:Humans; D007166:Immunosuppressive Agents; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000037:antagonists & inhibitors*; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D009000:Monocytes / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D011971:Receptors, Immunologic / Q000378:metabolism; D015375:Receptors, Interleukin-2; D011990:Receptors, Transferrin / Q000378:metabolism; D015291:Transforming Growth Factors
chemical_list: D007166:Immunosuppressive Agents; D007375:Interleukin-1; D007376:Interleukin-2; D010455:Peptides; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D011990:Receptors, Transferrin; D015291:Transforming Growth Factors