TNF and rheumatoid arthritis: This cluster might be an ectopic lymphoid-like structure (ELS), which is linked to deleterious outcomes in certain autoimmune conditions.41 In RA, for example, it is associated with inadequate response to anti-TNF.42 Concurrently, in inflamed CD lesions, activated CD4+ T cells are part of a module that mediates nonresponsiveness to anti-TNF.33