Biological characterization of a monoclonal antibody TB 21 against human transforming growth factor-beta 1.

A hybridoma TB 21 clone was derived from fusion between Sp 2/0-Ag 14 myeloma cells and spleen cells of BALB/c mice immunized with transforming growth factor-beta 1 (TGF-beta 1) purified from human platelets. The TB 21 clone was identified to produce monoclonal antibody with IgG1 subclass and had sufficient titer for immunoreactivity to both human platelets-derived TGF-beta 1 and recombinant human TGF-beta 1 by enzyme-linked immunosorbent assay (ELISA). Western blotting studies demonstrated that two immunoreactive bands corresponding to 25 Kda and 12.5 Kda molecules were observed in the sample of acid/ethanol extracts from human platelets. The affinity constant (Kaff) was determined as 1.47 x 10(8) M-1 with non-competitive ELISA. Moreover, using bioassay for the effects of TGF-beta 1 on the growth of mink lung epithelial cells (CCL/64 cell line) and fibroblast cells (NRK 49 F cell line), TB 21 IgG was shown to be able to neutralize the action of TGF-beta 1 on the growth of these target cells. Therefore, this monoclonal antibody may be a useful probe for studying the growth modulatory activity of TGF-beta 1 in a variety of cells and tissues.