TNF and Crohn ileitis: The increased TNF, whose expression is initiated by signals from the microbiome, promotes ileitis.11, 12, 13 The TLS that form during disease progression obstruct the trafficking of immune cells and molecular cargo to draining lymph nodes and promote both leakage of lymph as well as backflow of lymphatic cargo towards adjacent regions of the intestine.9 We are left to wonder whether preventing TLS formation would reduce ileitis.