CYTOKINE REGULATION OF SECONDARY LYMPHOID ORGAN DEVELOPMENT

Lymphotoxin and tumor necrosis factor provide essential signals for th e formation of secondary lymphoid tissue structures. Lymphotoxin in it s membrane form (LT alpha(1) beta(2) heterotrimer) is required for the development of lymph nodes and Peyer's patches and supports the devel opment of normal spleen structure, In the spleen, lymphotoxin acts dur ing embryonic development to support the formation of distinct B and T cell zones. Lymphotoxin also acts in a tonic fashion-supporting the f ormation and maintenance of the follicular dendritic cell network and of primary B cell follicle structure, The cells that deliver the tonic lymphotoxin signal supporting follicular dendritic cell structure are B cells; thus, B cells participate fundamentally in the development o f the lymphoid tissue structure in which they subsequently mature.