2.8 Enzyme-linked immunosorbent assay (ELISA)
The expression of TGF-β in the supernatant of the cell culture and Arg-1
in intracellular were detected using an ELISA kit (Cusabio, Wuhan,
China) according to the manufacturer’s instructions. The cell
supernatant and cell lysates were diluted in assay diluents and added to
the plates, which were then incubated for 2 h at 37 °C followed by the
addition of diluted detection antibody (100 μL/well). Plates were
rewashed, avidin-HRP was added, and the plates were incubated for 30
min. Next, the substrate solution was added and incubated for 15 min,
and the reaction was stopped with 100 μL of stop solution. Absorbance
was read at 450 nm for 20 min using an ELISA reader.