Involvement of lymphoid inducer cells in the development of secondary and tertiary lymphoid structure

Abstract

During development lymphoid tissue inducer (LTi) cells are the first hematopoietic cells to enter the secondary lymphoid anlagen and induce lymphoid tissue neogenesis. LTi cells induce lymphoid tissue neogensis by expressing a wide range of proteins that are associated with lymphoid organogenesis. Among these proteins, membrane-bound lymphotoxin (LT) alpha1beta2 has been identified as a critical component to this process. LTalpha1beta2 interacts with the LTbeta-receptor on stromal cells and this interaction induces up-regulation of adhesion molecules and production of chemokines that are necessary for the attraction, retention and organization of other cell types. Constitutive expression of LTalpha1beta2 in adult LTi cells can result in the formation of a lymphoid-like structure called tertiary lymphoid tissue. In this review, we summarize the function of fetal and adult LTi cells and their involvement in secondary and tertiary lymphoid tissue development in murine models.