Stromal and hematopoietic cells in secondary lymphoid organs: partners in immunity

• Published in: Immunological reviews Vol. 251; no. 1; pp. 160 - 176
• Main Authors: Malhotra, Deepali, Fletcher, Anne L., Turley, Shannon J.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.01.2013
• Subjects: Adaptive Immunity; Animals; Antigen Presentation; Antigen-presenting cells; blood endothelial cell; CD8 antigen; Cell Communication - immunology; Cell interactions; Cell migration; Cell Movement - immunology; Chemokines; Chemokines - immunology; dendritic cell; Dendritic cells; fibroblastic reticular cell; Hematopoietic Stem Cells - immunology; Hemopoiesis; Humans; Immune response; Immunity; Immunological tolerance; Inflammation; integrin α7+ pericyte; Lymph nodes; Lymph Nodes - immunology; lymphatic endothelial cell; Lymphocyte Activation; Lymphocytes T; Parenchyma; Peyer's patches; scaffolds; Spleen; stromal cells; Stromal Cells - immunology; T cell; tolerance/suppression
• ISSN: 0105-2896; 1600-065X
• DOI: 10.1111/imr.12023

Summary Secondary lymphoid organs (SLOs), including lymph nodes, Peyer's patches, and the spleen, have evolved to bring cells of the immune system together. In these collaborative environments, lymphocytes scan the surfaces of antigen‐presenting cells for cognate antigens, while moving along stromal networks. The cell‐cell interactions between stromal and hematopoietic cells in SLOs are therefore integral to the normal functioning of these tissues. Not only do stromal cells physically construct SLO architecture but they are essential for regulating hematopoietic populations within these domains. Stromal cells interact closely with lymphocytes and dendritic cells, providing scaffolds on which these cells migrate, and recruiting them into niches by secreting chemokines. Within lymph nodes, stromal cell‐ensheathed conduit networks transport small antigens deep into the SLO parenchyma. More recently, stromal cells have been found to induce peripheral CD8+ T‐cell tolerance and control the extent to which newly activated T cells proliferate within lymph nodes. Thus, stromal‐hematopoietic crosstalk has important consequences for regulating immune cell function within SLOs. In addition, stromal cell interactions with hematopoietic cells, other stroma, and the inflammatory milieu have profound effects on key stromal functions. Here, we examine ways in which these interactions within the lymph node environment influence the adaptive immune response.