FTL and acute respiratory distress syndrome: Given our above findings that FTH1 is increased in human and murine macrophages in ARDS, and that mice who have little macrophage FTH1 are protected from ferroptosis under hyperoxia likely due to the increased secretion of FTL which sequesters extracellular iron, we sought to determine the molecular composition of the increased serum ferritin in human COVID-19.