IL22 and bacterial pneumonia: Recently, type 3 innate lymphoid cells (ILC3s) have been identified as the main source of innate IL-22.3 IL-22 is expressed in healthy human lung tissue, and patients with sarcoidosis and ARDS have decreased IL-22 levels.3 Innate IL-22 is protective against acute epithelial damage and inflammation in the lung as neutralisation of IL-22 exacerbates bacterial and viral infections and exogenous IL-22 attenuates bacterial pneumonias.4