Use of a DNA microfluorometric assay to measure proliferative response of mink lung cells to purified TGF beta and to TGF beta activity found in prostate cell conditioned medium.

The proliferative response of Mv1Lu cells to purified TGF beta 1, or TGF beta-like activity released by various cells into medium conditioned over a 24-h period was quantitated by adapting a rapid DNA fluorometric assay. Acid activation of the conditioned medium allowed the amount of biologically latent versus active TGF beta to be quantitated. A neutralizing antibody specific for TGF beta 1, 1.2, and 2.0 completely blocked the growth inhibition observed treating Mv1Lu cells with either purified TGF beta 1 or medium containing secreted TGF beta-like activity conditioned by DU145 prostate cells. In contrast to other assays commonly used to measure TGF beta activity, the proliferative response is related directly to DNA content rather than as a reflection of enzymatic activity or incorporation of 3H-thymidine. The necessity for radioactive isotope usage has been eliminated, and the biological response can be quantitated over a period of days.