The LTβR ligand TNFSF14 was increased in the bronchoalveolar lavage (BAL) fluid and was present throughout the lung parenchyma in influenza-infected mice, and patients with influenza or COVID-19 acute respiratory distress syndrome (ARDS) had elevated levels of TNFSF14 in BAL fluids compared with healthy controls. The gene discussed is LTBR; the disease is influenza.