Characterization of nonlymphoid cells derived from rat peripheral lymph

Abstract

Mesenteric lymphadenectomy in rats is followed by union of peripheral and central lymphatics, allowing the collection of intestine-derived peripheral lymph cells via the thoracic duct for several days. These cells include a proportion of nonlymphoid cells (NLC) that show irregular and heterogeneous surface morphology including long pseudopodia and veils. They stain variably for nonspecific esterase and acid phosphatase and are ATPase-positive. Their nuclei are irregular and some contain cytoplasmic inclusions, some of which show peroxidase activity and/or contain DNA. NLC have a range of densitites generally lower than that of lymphocytes. Freshly collected NLC express the leukocyte-common antigen (defined by monoclonal antibody MRC Ox 1) and Ia antigens (I-A and I-E subregion products defined by monoclonal antibodies) but they show a relative lack of other surface markers normally found on rat B or T lymphocytes (W3/13, W3/25, MRC Ox 12 (sIg), MRC Ox 19) or rat macrophages (FcR, C'R, mannose R, W3/25). In general NLC are only weakly adherent to glass or plastic. Although a subpopulation of NLC appear to have had a phagocytic past, freshly collected NLC fail to phagocytose a variety of test particles in vitro. NLC also appear incapable of pinocytosis in vitro. This heterogeneity may represent distinct subpopulations of NLC or different stages in the development of a single cell lineage. Direct cannulation of mesenteric lacteals shows that the majority of NLC are derived from the small intestine and their precursors appear to be present both in lamina propria and Peyer's patches. Kinetic studies, following irradiation or intravenous tritiated thymidine, show that the majority of NLC turn over rapidly in the intestine with a modal time of 3-5 d. Studies with bone marrow chimeras show that they are derived from a rapidly dividing precursor present in normal bone marrow. NLC occur at very low frequencies in normal thoracic duct lymph at all times following cannulation. The evidence presented suggests that NLC closely resemble mouse lymphoid dendritic cells. This conclusion is supported by evidence already obtained showing that NLC are potent stimulators of the semi-allogeneic rat primary mixed leukocyte reaction. In addition to the ceils resembling dendritic cells rare monocytoid cells are found in thoracic duct lymph of lymphadenectomized specific pathogen-free rats. The proportion of these cells increases greatly when the animals are conventionally housed. It seems probable that the physiological function of NLC is to act as accessory cells in the lymph nodes to which they normally drain. Methods for enriching NLC and thus facilitating analysis of their functions are discussed.

A distinct subset of intestinal dendritic cells responds selectively to oral TLR7/8 stimulation

“…However, little is known about TLR expression on and responsiveness of migrating DC (and potential subsets thereof), as they cannot be studied easily in mice or humans. In this study we have examined these migrating intestinal DC directly in lymph using our unique model [23]. We extend our previous studies and show that DC migrating from the small intestine comprise three distinct subsets.…”

“…Rats used were males 12-24 wks of age. Mesenteric and coeliac lymphadenectomy (MLNX and CoeLNX, respectively) and thoracic duct cannulation were performed as described previously [23,31]. All procedures were carried out in accordance with Home Office guidelines.…”

Site‐specific expression of CD11b and SIRPα (CD172a) on dendritic cells: implications for their migration patterns in the gut immune system

“…CD11b + and CD11b -DC subsets are found in mice and rats as fixed subsets [9,12], and it was recently demonstrated that CD11b is not involved in the regulation of DC migration in rats [30]. Although Pugh et al [11] detected more DC in afferent lymph draining lengths of rat intestine with PP than of those without PP, this difference was not shown as significant, and DC were identified only by morphology in their study. Notably, even in lengths of gut containing PP, a large amount of tissue is normal LP.…”

“…However, it is still largely unknown where these antigenbearing cells originate from: Shreedhar et al claim that the major source of migrating DC in lymph is the LP [4], where DC can sample antigens from the gut lumen by extending dendrites into the epithelium [10]. Conversely, Pugh et al observed a larger number of DC in lymph draining from PP regions than in lymph draining from the normal LP [11]. In different compartments of the murine intestinal tract, phenotypically distinct DC subsets have been identified [12,13].…”

Migration of immature mouse DC across resting endothelium is mediated by ICAM‐2 but independent of β2‐integrins and murine DC‐SIGN homologues

“…Here they initiate specific immune responses against the loaded antigens by presenting them in combination with costimulatory molecules to antigenspecific lymphocytes [5]. In non-inflamed tissues, DC have a turn-over time of several days to several weeks [6][7][8], requiring a constant replenishment of DC in the tissues by emigration of precursor/immature DC from the blood [9]. The molecules which are involved in this process of homeostatic extravasation of DC across resting endothelium remain ill-defined.…”