A novel, sensitive bioassay for transforming growth factor beta.

We have developed a simple, sensitive bioassay for transforming growth factors beta 1 and beta 2 (TGF-beta 1 and TGF-beta 2) based on the ability of these cytokines to inhibit the interleukin-5 induced proliferation of the erythroleukaemia cell line, TF-1. This assay is rapid, reproducible and sensitive to less than 500 fg/ml of TGF-beta 1, and 5-10 pg/ml TGF-beta 2. The assay is 100-1000-fold less sensitive to other inhibitory molecules such as interferon-beta, interferon-gamma and TNF-alpha. The assay can be made specific for TGF-beta 1 or TGF-beta 2 by including specific neutralising antibodies for TGF-beta 1 or TGF-beta 2. The assay can recognise all the readily available recombinant molecular species of these molecules as well as the natural proteins produced from human and bovine platelets and detects TGF-beta in serum samples.