IL22 and infection: IL-22 was thus shown to be important for inducing a protective host immunity to the extracellular gram-negative pathogens K. pneumoniae in the lung and C. rodentium in the intestine [41], [47] but did not have an important role in the host defense against infection with M. tuberculosis, Mycobacterium avium, L. monocytogenes and S. mansoni[48], [49].