Meal-contingent intestinal lymph sampling from awake, unrestrained rats

Standard procedures for intestinal lymph collection involve continuous, quantitative drainage of the lymph fluid in anesthetized or restrained animals that are often euthanized within 48 h. We here describe a novel technique for the nonocclusive cannulation of the major intestinal lymph duct in rats that allows for repetitive in vivo sampling of intestinal lymph from unrestrained, awake, and ad libitum-fed animals. The distinctive feature of this novel technique is that a 5- to 7-mm long piece of Vialon tubing (OD/ID: 0.8/0.7 mm) with a small hole in its wall is first implanted into the major intestinal lymph duct for stabilization. The tapered tip (OD: ≈0.1 mm) of the catheter is then inserted into the hole of the tubing and fixed in place with a polyamid suture and a drop of tissue glue. In our hands, catheters implanted this way remain patent for up to 6 wk after surgery. In an initial experiment we collected lymph from six adult rats before (0) and 15, 30, 45, 60, 75, 90, 120, and 180 min (120 μl, each) after the onset of isocaloric (12.5 kcal) low-fat (LF) or high-fat (HF) test meals and measured active glucagon-like peptide-1 (GLP-1). Intestinal lymphatic GLP-1 concentration increased (P < 0.05) from ≈4 pmol/l (0 min) to a peak of 33 ± 6 (means ± SE) or 22 ± 4 pmol/l at 15 (HF) or 30 min (LF) after meal onset and gradually returned to baseline levels by 180 min. With this new technique fewer animals are required to generate physiologically relevant data for various aspects of gastrointestinal physiology that involve the lymphatic system. Furthermore, the advantage of this system is that the animal can act as its own control when the effect of different experimental protocols is tested.     

内耳淋巴液的来源、性质和成分

内耳淋巴液中外淋巴液的来源有2种说法:①来源于脑脊液;②来自毛细血管的血液超滤液。内淋巴可能是以分泌方式产生的,二者性质与成分存在一定的差异     

Topography,ultrastructure and phagocytic capacity of avian lymph nodes

Summary The structure of the avian lymph node (ALN) is characterized by a thin capsule, thin lymphoreticular cords, and an absence of trabeculae. It is not possible to subdivide the ALN into cortex, paracortex and medulla, or to subdivide the system of sinuses into marginal, trabecular and medullary divisions. The lymphoreticular cords contain avian germinal centers (AGC) with B-lymphocytes and the area of T-lymphocytes.Postcapillary venules are responsible for the recirculation of lymphocytes. Sinus reticular cells do not exist in the ALN, but free macrophages are present. The phagocytic capacity of the macrophages was determined by injection of vital dyes (India ink, Berlin blue) and inoculation with Candida cells. Macrophages filled with markers migrate from the lymph sinuses into the lymphoreticular cords and further into the AGC. The mobility of the macrophages is remarkably lower after phagocytosis of Candida cells.This study is dedicated to Prof. Dr. Dr. h.c. Hugo Grau (Weilheim) with sincere appreciation and respect     

Plaque forming cells in the spleen,lymph and blood

The capacity of blood and lymphatic cells and of the spleen in rabbits immunized with sheep red blood cells to produce antibodies (PFC) has been studied. In rabbits in which only the blood was examined, the numbers of PFC reached a peak 4 days after one immunization, or 3 days after two immunizations. Moreover, double immunization yielded 10 times higher numbers of PFC than single immunization. Comparative studies of the blood, lymph and spleen revealed largest numbers of PFC in the spleen, smaller in the blood, and fewest in the lymph. This pattern was observed after single as well as double immunization, although the proportions were different after double immunization. After the second immunization much larger numbers of PFC appeared, increasing especially in the lymph. Discrepancies between the findings and earlier results, and the problem of the mechanisms of permeation of immunologically competent cells into the blood are discussed.     

The human peripheral lymph node vascular addressin is a ligand for LECAM-1, the peripheral lymph node homing receptor

The trafficking of lymphocytes from the blood and into lymphoid organs is controlled by tissue-selective lymphocyte interactions with specialized endothelial cells lining post capillary venules, in particular the high endothelial venules (HEV) found in lymphoid tissues and sites of chronic inflammation. Lymphocyte interactions with HEV are mediated in part by lymphocyte homing receptors and tissue-specific HEV determinants, the vascular addressins. A peripheral lymph node addressin (PNAd) has been detected immunohistologically in mouse and man by monoclonal antibody MECA-79, which inhibits lymphocyte homing to lymph nodes and lymphocyte binding to lymph node and tonsillar HEV. The human MECA-79 antigen, PNAd, is molecularly distinct from the 65-kD mucosal vascular addressin. The most abundant iodinated species by SDS-PAGE is 105 kD. When affinity isolated and immobilized on glass slides, MECA-79 immunoisolated material binds human and mouse lymphocytes avidly in a calcium dependent manner. Binding is blocked by mAb MECA-79, by antibodies against mouse or human LECAM-1 (the peripheral lymph node homing receptor, the MEL-14 antigen, LAM-1), and by treatment of PNAd with neuraminidase. Expression of LECAM-1 cDNA confers PNAd binding ability on a transfected B cell line. We conclude that LECAM-1 mediates lymphocyte binding to PNAd, an interaction that involves the lectin activity of LECAM-1 and carbohydrate determinants on the addressin.     

Immunosurveillance by hematopoietic progenitor cells trafficking through blood, lymph, and peripheral tissues

Constitutive egress of bone marrow (BM)-resident hematopoietic stem and progenitor cells (HSPCs) into the blood is a well-established phenomenon, but the ultimate fate and functional relevance of circulating HSPCs is largely unknown. We show that mouse thoracic duct (TD) lymph contains HSPCs that possess short- and long-term multilineage reconstitution capacity. TD-derived HSPCs originate in the BM, enter the blood, and traffic to multiple peripheral organs, where they reside for at least 36 hr before entering draining lymphatics to return to the blood and, eventually, the BM. HSPC egress from extramedullary tissues into lymph depends on sphingosine-1-phosphate receptors. Migratory HSPCs proliferate within extramedullary tissues and give rise to tissue-resident myeloid cells, preferentially dendritic cells. HSPC differentiation is amplified upon exposure to Toll-like receptor agonists. Thus, HSPCs can survey peripheral organs and can foster the local production of tissue-resident innate immune cells under both steady-state conditions and in response to inflammatory signals.     

Intrathoracic sources of caudal mediastinal lymph node efferent lymph in sheep

We investigated the intrathoracic contributions to the caudal mediastinal lymph node (CMN) efferent lymph in 12 anesthetized sheep after removing possible systemic contributions from below the diaphragm. We interrupted various pathways that may send lymph to the CMN (chest wall, esophagus, lung). Because the experiment is destructive, we did the resections in various combinations and waited 1 h between steps. Base-line CMN efferent lymph flow averaged 0.90 +/- 0.52 g/15 min (mean +/- SD). Cutting the pulmonary ligaments bilaterally caused lymph flow to decrease by an average of 58%. In five sheep, cauterizing around the lung hila reduced lymph flow by 16% of base line, cauterizing along the esophagus reduced lymph flow by 18% of base line, and cauterizing along the chest wall increased lymph flow by 6% of base line. After complete isolation of the node, except for the bronchoesophageal artery, dorsal mediastinal vein, and CMN efferent duct, 14% of base-line flow remained. The lymph-to-plasma total protein concentration ratios did not change significantly with any procedure. Under the conditions of our experiments, approximately 74% of base-line intrathoracic CMN efferent flow comes from the lung.     

Influence of the composition of rat central lymph on the pharmacokinetics (the steady state during infusion, bioavailability, absorption) of diazepam, studied in the blood and lymph

Diazepam was administered by infusion to three groups of rats with an induced differentiated total lipid content in their lymph (unfed, fed, oil-fed) and its lymph/blood concentration ratios in the steady state were determined. Ratio values were highest in the group with the highest lymph lipid content (the oil-fed group, 2.20 +/- 0.08) and fell significantly in the other groups (fed group 1.46 +/- 0.09, unfed group 1.15 +/- 0.05). The areas under the blood and lymph concentration curves after the intravenous (i.v.) and intraduodenal (i.d.) administration of diazepam were used to determine absolute (F) and lymphatic (FL) bioavailability. The F value in the blood can be raised by increasing the amount of lipids, whereas in the lymph, under the same conditions, it falls. During the i.v. and i.d. administration of diazepam, FL always rises with an increase in the amount of lipids in the lymph. The role played by the lymphatic system in total diazepam absorption was determined from the experimental results of its i.d. administration. The absolute values are very low (0.043-0.316%), but are significantly influenced by the presence of lipids.