**4. Characterization of monoclonal anti-TGF–β antibody**

The reactivity of the produced monoclonal antibodies with Urine TGF–β was screened by enzyme-linked immunosorbent assay (ELISA) using kit produced by Section living creature technique limited company of Hangzhou, China (NO,13409007) The sample solution (40 µl) was incubated with the monoclonal anti- TGF–β antibody (40 µl) at room temperature for 1 h in an TGF–β–transferrin attached microplate. After washing with phosphate-buffered saline (PBS) containing 0.05% Tween 20, 0.1 ml of peroxidase-labelled goat F(ab')2 fragment to mouse IgG(Fc) was added into the microplate, followed by incubation at room temperature for 1 h. After washing with PBS containing 0.05% Tween 20, 0.2 ml of ophenylenediamine hydrochloride (1 mg/ml) containing 0.0124% H2O2 was added to the microplate, and then incubated at room temperature for 30 min. The reaction was terminated with 1.3 M H2SO4. The absorption at 492 nm was measured.
