Four mAb able to recognize transforming growth factor-beta 2 (TGF-beta)2 were obtained. One of these mAb, 1D11.16, was able to neutralize the biological activity of both TGF-beta 1 and beta 2 in vitro. This was demonstrated in an Il-1, PHA-dependent thymocyte mitogenic assay that is inhibitable by TGF-beta in a dose-dependent manner. All four mAb recognized the dimeric form of TGF-beta 2 in Western blots. The mAb were also found to immunoprecipitate [125I]-TGF-beta 2. mAb 3C7.14 coupled to Sepharose could efficiently immunoaffinity purify TGF-beta 2 from a complex mixture of proteins. Affinity constants were determined for the four mAb and they ranged from 3.4 x 10(8) to 1.6 x 10(7) L/mol.