Measurement of TGF-beta in biological fluids.

Transforming growth factor (TGF-beta) is an immunoregulatory cytokine produced by many different cell types, including lymphocytes and monocytes-macrophages. Two assays are described for the quantitation of TGF-beta activity in supernatant fluids. The bioassay for TGF-beta is based on the potent ability of TGF-beta to suppress lymphocyte proliferation. The radioreceptor assay is based on the ability of TGF-beta-containing supernatant fluids to inhibit the binding of radiolabeled TGF-beta to its cellular receptor. Two support protocols describe acid-activation and neutralization of TGF-beta.