Reactive oxygen species (ROS) are suggested to play a pivotal role in ILD. Little is known, however, about the endogenous antioxidant levels in ILD that can offer protection against ROS. It is expected that the high amount of ROS present in ILD will reduce the antioxidant levels. Therefore, antioxidant therapy to strengthen this reduced antioxidant defense might be efficacious in ILD treatment. Since ROS are capable of initiating and mediating inflammation, antioxidant therapy might also mitigate elevated inflammation. A candidate for antioxidant therapy is the flavonoid quercetin that is known for its anti-oxidative and anti-inflammatory capacities.

The aim of the present study is to determine the antioxidant and inflammatory status in ILD, i.e. sarcoidosis and idiopathic pulmonary fibrosis (IPF). Furthermore, to evaluate the possible anti-inflammatory effects of antioxidants, the effect of quercetin will be examined on the ex vivo LPS-induced cytokine production in ILD