Three types of macrophagic cells in the mesentery of mice with special referenceto LYVE-1-immunoreactive cells

Abstract

Immunohistochemistry using whole mount preparations of the murine mesentery revealed two types of LYVE-1-immunoreactive cells with dendritic morphology other than F4/80 + typical macrophages. The two types of LYVE-1 + cells were regularly distributed with constant intervals throughout the mesentery and appeared to possess their own territory. Both types of LYVE-1 + cells were weakly or moderately immunopositive for F4/80 antibody, a marker of macrophages, while F4/80 + round macrophages were absolutely free from the LYVE-1 immunoreactivity. Only macrophages could ingest latex particles of 20 nm in diameter 3 h after a peritoneal injection. Peritoneal administration of lipopolysaccharide (LPS) induced a rapid reduction of LYVE-1 immunoreactivity in the cells with dendritic morphology followed by an increased immunoreactivity to F4/80 antibody, and simultaneously by dynamic changes in their shape. Under normal conditions, F4/80 + macrophages in various connective tissues expressed LYVE-1, in contrast to lack of LYVE-1 in F4/80 + macrophages within the parenchyma of visceral organs and macrophages residing in hepatic sinusoids and pulmonary alveoli. LYVE-1 may play a role in cell adhesion and migration of macrophagic cells within connective tissues rich in hyaluronan, and loss of LYVE-1 becomes a reliable sign of activated conditions in inflammation.Membranous tissues such as the omentum and mesentery contain many macrophages and related cells, including Langerhans/dendritic cells. However, their distinct classification and functions remain unclear. As shown by their stainability with marker antibodies and enzymatic activities, cells with dendritic morphology in the rat omentum were very close to Ia antigen-positive interdigitating cells of lymphatic tissues (9). This study also noted that cells with dendritic morphology in the rat omentum were fairly heterogeneous (9). Zhu et al. (23) recognized the stellate or dendritic cells in the mouse omentum to be scavenging macrophages due to their phagocytic activity, stainability to marker antibodies, and severe reduction in number in op/op mice.

<b>The selective distribution of LYVE-1-expressing endothelial cells and reticular cells in the reticulo-endothelial system </b><b>(RES) </b>

“…Noteworthy, the expression of hyaluronidases there was restricted to macrophages but not reticular cells. Ultrastructually, LYVE-1 is always localized in the plasma membrane but not in the cytoplasm and cell organelle, in contrast to its cytoplasmic localization in macrophagic cells, such as intracellular vesicles and vacuoles (21,41). The dual membrane localization of LYVE-1 in the vascular endothelial cells is in agreement with early observations concerning LYVE-1 in the endothelium of lymphatics (29), suggesting transport via the cells (transcytosis) without intracellular degradation.…”

“…The dual membrane localization of LYVE-1 in the vascular endothelial cells is in agreement with early observations concerning LYVE-1 in the endothelium of lymphatics (29), suggesting transport via the cells (transcytosis) without intracellular degradation. Our immunohistochemical data showed that the LYVE-1-immunoreactive cells were topographically associated with a dense distribution of macrophages in each tissue: Kupffer cells in the hepatic sinusoids, LPS (41). In contrast, the present study showed that LPS stimulation conversely increased the expression of LYVE-1 in the endothelial cells of the liver and lung, as demonstrated by quantitative RT-PCR and immunostaining.…”

“…LYVE-1 has been believed to be a hyaluronan receptor molecule abundantly expressed in the endothelium of lymphatic vessels, with additional expressions in sinusoidal endothelia of the liver, lymph node, and spleen and in some macrophage lineages (1,3,21,26,41). However, we found a broader distribution of LYVE-1: vascular endothelial cells in the lung, adrenal gland, and endocardium.…”

Topography of Lymphatic Markers in Human Iris and Ciliary Body

“…If and how these contribute to the immunological situation in the eye is unknown, but could be related to the high content of vitreous hyaluronan, as speculated earlier in a nonocular mouse model. 63 Because podoplanin expression was also found in a subset of F4/80positive macrophages, 64 the here detected single podoplaninpositive cells therefore might also represent macrophages, however, due to antibody incompatibility, were unable to test for this. Regarding luminal structures with vessel-like character positive for podoplanin, these were very few and the immunoreactive signal was very weak compared with other signals.…”

Inhibition of tumor formation and metastasis by a monoclonal antibody against lymphatic vessel endothelial hyaluronan receptor 1

“…Although 38M and 64R reacted with lymphatic vessels in mouse tissues (Figure ) but not with blood vessels (Figure ), several studies have reported LYVE‐1 in CD11b‐ or F4/80‐positive macrophages . 38M and 64R, however, did not react with thioglycollate‐induced macrophages (data not shown), indicating that the epitopes recognized by 38M and 64R are preferentially expressed on the endothelia of lymphatic vessels.…”