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Insulin‐like growth factor I messenger RNA and protein are expressed in the human lymph node and distinctly confined to subtypes of macrophages, antigen‐presenting cells, lymphocytes and endothelial cells
Author(s) -
Oberlin Dominique,
Fellbaum Christian,
Eppler Elisabeth
Publication year - 2009
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1111/j.1365-2567.2009.03136.x
Subject(s) - biology , follicular dendritic cells , cd40 , paracrine signalling , lymph node stromal cell , immune system , antigen presenting cell , autocrine signalling , lymph node , antigen , growth factor , microbiology and biotechnology , t cell , immunology , cytotoxic t cell , cell culture , receptor , genetics , biochemistry , in vitro
Summary Insulin‐like growth factor I (IGF‐I) is a potent hormone that stimulates growth and differentiation and inhibits apoptosis in numerous tissues. Preliminary evidence suggests that IGF‐I exerts differentiating, mitogenic and restoring activities in the immune system but the sites of synthesis of local IGF‐I are unknown. Identification of these sites would allow the functional role of local IGF‐I to be clarified. The presence of IGF‐I in non‐immune cells suggests that it acts as a trophic factor, while its occurrence in subtypes of lymphocytes or antigen‐presenting cells indicates paracrine/autocrine direct regulatory involvement of IGF‐I in the human immune response. The present study investigated the location of IGF‐I messenger RNA and protein on archival human lymph node samples by in situ hybridization, immunohistochemistry and double immunofluorescence staining using an IGF‐I probe and antisera specific for human IGF‐I and CD3 (T lymphocytes), CD20 (B lymphocytes), CD68 (macrophages), CD21 (follicular dendritic cells), S100 (interdigitating dendritic cells) and podoplanin (fibroblastic reticular cells). Numerous cells within the B‐ and T‐cell compartments expressed the IGF‐I gene, and the majority of these cells were identified as macrophages. Solitary follicular dendritic cells exhibited IGF‐I. A few T lymphocytes, and no B lymphocytes, contained IGF‐I immunoreactive material. Furthermore, IGF‐I immunoreactive cells outside the follicles that did not react with CD3, CD20, S100 or podoplanin markers were identified as high‐endothelial venule (HEV) cells. From this we conclude that the main task of IGF‐I in human non‐tumoral lymph node may be autocrine and paracrine regulation of the differentiation, stimulation and survival of lymphocytes, antigen‐presenting cells and macrophages and the differentiation and maintenance of HEV cells.