Fascin-positive dendritic cells and fibroblastic reticulum cells build a framework of T-cell areas in lymph nodes.
ABSTRACT Fascin, a 55-kDa actin-bundling protein, and alpha-smooth muscle actin (ASMA) were immunohistochemically examined in murine normal and stimulated lymph nodes. In specific pathogen-free young female mice, a few fascin-positive cells (FPCs) were located in the sinus and surrounding tissues, but ASMA-positive cells were undetectable. Following a subcutaneous injection of sheep red blood cells, the numbers of FPCs and their dendrites increased in the paracortex, with the accumulation of activated lymphocytes. Fibroblastic reticulum cells (FRCs), endothelial cells, histiocytic cells and lymphocytes in various stages of maturation were all fascin negative. These results indicated that fascin could be a reliable marker of paracortical dendritic cells in murine lymph nodes. However, FRCs became ASMA positive. Immunoelectron microscopy showed that the FPCs were interdigitating cells and that they closely contacted with FRCs. These two types of cells and reticular fiber formed a network in the paracortex and contacted with each other. In active paracortical response, both FPCs and FRCs are also stimulated and might play a significant role in the maturation of the lymphocytes.
- [show abstract] [hide abstract]
ABSTRACT: Morphology, phenotype, and enzyme activity of highly enriched (80%) unlabeled human epidermal Langerhans cells (LC) have been studied, with emphasis on changes during a short-term culture of three days in vitro. All freshly isolated LC contained Birbeck granules and expressed high levels of CD1a, CD1c, and MHC class II molecules HLA-DR, -DP, and -DQ. They have a weak to moderate expression of RFD1, C3biR, Fc gamma R, p 150/95, MHC class I molecules HLA-ABC, and of the adhesion molecules LFA-3 and ICAM-1, whereas no expression of LFA-1 and several monocyte/macrophage markers were detected. Human LC undergo profound changes during in vitro culture. Birbeck granules, C3biR, Fc gamma R, and p 150/95 were completely lost and the expression of CD1a and CD1c was markedly decreased or lost. Expression of molecules that have essential functions in antigen presentation remained present at the same level (MHC class II molecules and ICAM-1) or was markedly enhanced (LFA-3 and MHC class I). Highly remarkable was the dramatically enhanced expression of interdigitating cell marker RFD1. The monocyte/macrophage markers initially absent remained absent and the enzyme activity initially present (including ATPase and nonspecific esterase) remained present. In conclusion, the results in this report stress rapid alterations of human LC during in vitro culture, resulting in transformation into cells that have phenotypical characteristics of potent antigen presenting cells that resemble interdigitating cells.Journal of Investigative Dermatology 03/1990; 94(2):166-73. · 6.19 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Cell adhesion to individual macromolecules of the extracellular matrix has dramatic effects on the subcellular localization of the actin-bundling protein fascin and on the ability of cells to form stable fascin microspikes. The actin-binding activity of fascin is down-regulated by phosphorylation, and we used two differentiated cell types, C2C12 skeletal myoblasts and LLC-PK1 kidney epithelial cells, to examine the hypothesis that cell adhesion to the matrix components fibronectin, laminin-1, and thrombospondin-1 differentially regulates fascin phosphorylation. In both cell types, treatment with the PKC activator 12-tetradecanoyl phorbol 13-acetate (TPA) or adhesion to fibronectin led to a diffuse distribution of fascin after 1 h. C2C12 cells contain the PKC family members alpha, gamma, and lambda, and PKCalpha localization was altered upon cell adhesion to fibronectin. Two-dimensional isoelectric focusing/SDS-polyacrylamide gels were used to determine that fascin became phosphorylated in cells adherent to fibronectin and was inhibited by the PKC inhibitors calphostin C and chelerythrine chloride. Phosphorylation of fascin was not detected in cells adherent to thrombospondin-1 or to laminin-1. LLC-PK1 cells expressing green fluorescent protein (GFP)-fascin also displayed similar regulation of fascin phosphorylation. LLC-PK1 cells expressing GFP-fascin S39A, a nonphosphorylatable mutant, did not undergo spreading and focal contact organization on fibronectin, whereas cells expressing a GFP-fascin S39D mutant with constitutive negative charge spread more extensively than wild-type cells. In contrast, C2C12 cells coexpressing S39A fascin with endogenous fascin remained competent to form microspikes on thrombospondin-1, and cells that expressed fascin S39D attached to thrombospondin-1 but did not form microspikes. Blockade of PKCalpha activity by TPA-induced down-regulation led to actin association of wild-type fascin in fibronectin-adherent C2C12 and LLC-PK1 cells but did not alter the distribution of S39A or S39D fascins. The association of fascin with actin in fibronectin-adherent cells was also evident in the presence of an inhibitory antibody to integrin alpha5 subunit. These novel results establish matrix-initiated PKC-dependent regulation of fascin phosphorylation at serine 39 as a mechanism whereby matrix adhesion is coupled to the organization of cytoskeletal structure.Molecular Biology of the Cell 01/2000; 10(12):4177-90. · 4.60 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: For the electron microscopic identification of asialo GM1-positive cells, fresh-frozen sections fixed with cold acetone and PLP-fixed vibratome sections of adult rat livers were prepared immunocytochemically using the avidin-biotin-peroxidase complex method. Asialo GM1-positive cells were located mainly in the sinusoids, and rarely in Glisson's sheath and portal veins. In the sinusoids, most pit cells, showing the ultrastructural characteristics of large granular lymphocytes (LGL), were positive for asialo GM1 but a few pit cells were asialo GM1-negative. There were several, morphological differences between asialo GM1-positive and -negative pit cells. The asialo GM1-negative pit cells were smaller and had less-developed cell organelles and fewer dense granules, suggesting a more immature stage of development. Almost all the monocytes, segmented neutrophils and eosinophils, and small or large lymphocytes in the sinusoids also showed positive reaction for asialo GM1. In Glisson's sheath, in addition to pit cells and lymphocytes, mast cells were also positive for asialo GM1. In contrast, fixed cells such as liver parenchymal cells, endothelial cells, Kupffer cells and Ito cells within the liver lobules, as well as biliary epithelial cells, smooth muscle cells, fibroblasts, endothelial cells and pericytes in Glisson's sheath were all negative for asialo GM1. Thus, cell surface asialo GM1 expression is not specific for pit cells (LGL) in the rat liver.Virchows Archiv B Cell Pathology 02/1991; 60(6):389-98.