IL17A and rheumatoid arthritis: Similarly, the development of lung ectopic lymphoid tissues containing B cell follicles during infection (e.g., tuberculosis) or chronic inflammation (e.g., rheumatoid arthritis, COPD), is driven by CD4+ Th-17 cells and associated IL-17 cytokines, by promoting CXCL13 release and B and T cell infiltration [29]–[30].