For example, IL‐17 drives the development of TLSs (called induced bronchus associated lymphoid tissue; iBALT) in the lungs of neonatal mice challenged with lipopolysaccharide.41 Comparable studies show that the formation of iBALT in response to Pseudomonas aeruginosa infection is IL‐17 dependent.40 However, the development of iBALT following infection with modified vaccinia virus Ankara was unimpaired in the absence of IL‐17.40, 45 A similar context‐dependent role for IL‐17 in TLS development is observed in models of autoimmunity. The gene discussed is IL17A; the disease is Autoimmunity.