- Lymphotoxin and TNF produced by B cells are dispensable for maintenance of the follicle-associated epithelium but are required for development of lymphoid follicles in the Peyer's patches. Tumanov, A.V., Kuprash, D.V., Mach, J.A., Nedospasov, S.A., Chervonsky, A.V. J. Immunol. (2004)