different expression systems including prokaryotic, protozoan, fungal (yeasts), plant, insect and mammalian cells. Human IFN-γ is commonly expressed in Escherichia coli, marketed as ACTIMMUNE®, however, the resulting product of the prokaryotic expression system is not glycosylated with a short half-life in the bloodstream after injection; the purification process from bacterial expression system is also very costly. Other expression systems like Pichia pastoris did not show satisfactory results in terms of yields. Therapeutic use Interferon-γ 1b is approved by the U.S. Food and Drug Administration to treat chronic granulomatous disease (CGD) and osteopetrosis. The mechanism by which IFN-γ benefits CGD is via enhancing the efficacy of neutrophils against catalase-positive bacteria by correcting patients' oxidative metabolism. It was not approved to treat idiopathic pulmonary fibrosis (IPF). In 2002, the manufacturer InterMune issued a press release saying that phase III data demonstrated survival benefit in IPF and reduced mortality by 70% in patients with mild to moderate disease. The U.S. Department of Justice charged that the release contained false and misleading statements. InterMune's chief executive, Scott Harkonen, was accused of manipulating the trial data, was convicted in 2009 of wire fraud, and was sentenced to fines and community service. Harkonen appealed his conviction to the U.S. Court of Appeals for the Ninth Circuit, and lost. Harkonen was granted a full pardon on January 20, 2021. Preliminary research on the role of IFN-γ in treating Friedreich's ataxia (FA) conducted by Children’s Hospital of Philadelphia has found no beneficial effects in short-term (< 6-months) treatment. However, researchers in Turkey have discovered significant improvements in patients' gait and stance after 6 months of treatment. Although not officially approved, Interferon-γ has also been shown to be effective in treating patients with moderate to severe atopic dermatitis. Specifically, recombinant IFN-γ therapy has shown promise in patients with lowered IFN-γ expression, such as those with predisposition to herpes simplex virus, and pediatric patients. Potential use in immunotherapy IFN-γ increases an anti-proliferative state in cancer cells, while upregulating MHC I and MHC II expression, which increases immunorecognition and removal of pathogenic cells. IFN-γ also reduces metastasis in tumors by upregulating fibronectin, which negatively impacts tumor architecture. Cancer immunotherapy The goal of cancer immunotherapy is to trigger an immune response by the patient's immune cells to attack and kill malignant (cancer-causing) tumor cells. Type II IFN deficiency has been linked to several types of cancer, including B-cell lymphoma and lung cancer.