Transforming growth factor beta 1 (TGF‐β1) receptor expression on resting and mitogen‐activated T cells

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Abstract
Transforming growth factor β1 (TGF-β1) is a potent autocrine growth inhibitor of lymphocytes. In this study, the expression of TGF-β1 binding proteins was characterized on murine splenic T cells. With an affinity cross-linking method and by neutralizing antibodies to TGF-β1, [125I] TGF-β1 was found to bind to three cell surface–binding proteins (280–200 kD, 95–85 kD, 65 kD) that were differentially expressed on resting and mitogen-stimulated T cells. Freshly prepared (resting) T cells were found to constitutively express the 95–85-kD form of these binding proteins, whereas mitogenic stimulation by either concanavalin-A (Con-A), interleukin-1 (IL-1), interleukin-2 (IL-2), or 12-tetradencanoyl-phorbol-13-acetate (TPA) for 12–72 h induced the appearance of all forms of the TGF-β1 binding proteins (280–200 kD, 95–85 kD, and 65 kD). Furthermore, antibodies that neutralized the biologic action of TGF-β1 also blocked the binding of [125I] TGF-β1 to all three binding proteins, suggesting that these binding proteins are involved with signal transduction. These results suggest that the expression of the TGF-β1 receptor on T cells is regulated by T cell mitogenic signals and that a regulatory relationship may exist between T cell growth-promoting cytokines (IL-1 and IL-2) and the T cell growth inhibitor, TGF-β1.