Thioredoxin 1 is responsible for antibody disulfide reduction in CHO cell culture

► Disulfide bond reduction of a recombinant monoclonal antibody occurred during large-scale manufacturing. ► Expression of the cytosolic isoform of thioredoxin, TXN1, was knocked down by RNAi, which did not affect cell growth or viability. ► Knocking down expression of TXN1 significantly inhibits mAb reduction in CHO-K1 cell culture.