Lymphoid organogenesis in brief

Abstract

The recognition that lymphocytes existed in different varieties and that lymphoid organs were important for their differentiation greatly influenced immunological research. The growing awareness that started in the mid-fifties of the previous century has shifted the emphasis of immunology from a molecular, mostly serological science to the cell-oriented modern immunology of today. Matters such as hematopoietic differentiation, cell-cell interaction, cellular activation, as well as migratory behavior of hematopoietic cells received much attention and deepened our insight in the immune system. The relatively recent generation of mutant mice lacking lymphoid organs prompted the realization that the organogenesis of lymphoid organs could be dissected at the cellular and molecular level. Now we can distinguish several phases of development for lymphoid organs, and can assign molecules and cells to be essentially involved in these phases. Future research will identify additional molecules and cells required for the formation of the various lymphoid organs, because the picture is not complete yet.

Chemokine Receptor CXCR5 Supports Solitary Intestinal Lymphoid Tissue Formation, B Cell Homing, and Induction of Intestinal IgA Responses

“…In contrast, tertiary lymphoid tissue may form ectopically at any time in the adult organism once appropriate stimulation occurs, e.g., during chronic infections (recently reviewed in Ref. 14). In this study, we provide direct evidence that the positioning and density of SILT are fixed.…”

Roles of the NF- B Pathway in Lymphocyte Development and Function

“…Similar to the situation with mTECs, the classical pathway is likely required to induce expression of RelB and NF-kB2 to provide the components needed for continuous signaling via the alternative pathway (see previous discussion); in addition, the classical pathway may induce expression of Bcl-3. Little is known about how NF-kB controls the development/differentiation of stromal cells, such as FDCs, but as in mTECs, NF-kB does induce expression of chemokines essential for cellular interactions and compartmentalization in secondary lymphoid organs (Vondenhoff et al 2007;Mueller and Ahmed 2008;Randall et al 2008;Evans and Kim 2009;Suto et al 2009). Mature B cells express different forms of NF-kB.…”

“…Activation of the alternative pathway via LTbR in stromal (mesenchymal organizer) cells is essential for lymph node and Peyer's patch organogenesis (Drayton et al 2006;Elewaut and Ware 2007;Vondenhoff et al 2007). Similar to the situation in prenatal mTEC development, hematopoietic LTi cells initiate the process in part via expression of ligands for LTbR and RANK (Evans and Kim 2009); subsequently, B cells provide the necessary ligands (Elewaut and Ware 2007).…”

Induction of Colonic M Cells during Intestinal Inflammation

“…2 Most M cells [Peyer's patch (PP) type M cells] are found in the follicle-associated epithelium overlying organized lymphoid follicles, such as PP in the small intestine and nasopharynxassociated lymphoid tissue; a distinct M cell phenotype is the inducible villous M cell in the small intestine. 3,4 In contrast to villous M cells, the PP type M cells are associated with organized lymphoid follicles with an established stromal cell network. 5,6 During organogenesis, proinflammatory cytokines, such as tumor necrosis factor (TNF)-a and lymphotoxin-b, induce NF-kB stromal cell expression of a series of chemokines, including chemokine (C-C motif) ligands 19 and 21 and CXCL13, which facilitate the accumulation/ maintenance of the lymphoid follicle.…”