The degradation of bovine parathyroid hormone by leukocytes

Human peripheral leukocytes catalyse an elastase-like cleavage of bovine parathyroid hormone, with an identical specificity to that previously observed with a neutral proteinase (EC 3.4.21-) isolated from the outer surface of plasma membranes from human leukocytes. Parathyroid hormone is not hydrolysed by human erythrocytes, and polymorphonuclear leukocytes are much more effective in hormone degradation than lymphocytes. Despite the fact that purified human leukocyte granular elastase (EC 3.4.21.37) catalyses an identical cleavage reaction, the hydrolysis observed with intact cells is clearly not due to proteinases secreted by the cells. The reaction is inhibited by human serum and by purified human alpha-1-antitrypsin, but not by antibodies to human leukocyte granular elastase. The possible significance of these phenomena to the in vivo metabolism of parathyroid hormone are discussed.     

Blood lymphocyte and neutrophil function in patients with viral non-A, non-B hepatitis and a fecal-oral mechanism of the transmission of infection

A decrease in the capacity of lymphocytes for rosette formation, accompanied by a rise in the leukocyte count, has been found in patients with the severe form of hepatitis non A, non B. Neutrophils in these patients have shown a tendency towards an increased rosette formation. All altered characteristics normalized by the period of convalescence. As noted in this investigation, a considerable increase in the leukocyte count, along with an increase in the number of active rosette-forming neutrophils and a decrease in the capacity of leukocytes for rosette formation, is an unfavorable sign predicting the possibility of acute hepatic encephalopathy.     

Preparation of leukocyte-poor erythrocyte concentrates using a simple aspiration technic

Depletion of leukocytes from red blood cells can prevent transfusion reactions in HLA-sensitized patients. We describe a simple technique of aspiration of the buffy-coat after centrifugation of red blood cells concentrates, less than 6 days old. This method can remove 87% of the leukocytes. The average leukocyte count after aspiration is 2 x 10(8). This method is inexpensive and does not require any special equipment.     

Leukocytosis of exercise: role of cardiac output and catecholamines

The effect of propranolol (5 mg iv) on the leukocytosis of exercise was studied in seven normal young males. Leukocyte counts, plasma norepinephrine (NE), epinephrine (E), and cardiac output were measured at rest and in the steady state of several submaximal work loads when subjects exercised on a cycle ergometer. The results in control experiments were compared with those obtained on a different day with propranolol. Propranolol decreased heart rate at all work loads (P less than 0.001) but had no effect on the increase in cardiac output at increasing work loads. Plasma NE and E levels were similar at rest and in exercise in control and propranolol studies. There was no effect of propranolol on the increase in leukocyte counts with increasing work loads. Although propranolol did not affect the increase in total leukocyte count, the increase in lymphocyte count at higher work loads was less with propranolol. We conclude that the demargination of leukocytes from the pulmonary circulation in exercise is probably a mechanical effect of the increase in cardiac output. However, we have not excluded a contribution from a humoral event that would decrease the adherence of leukocytes to endothelium during exercise. The smaller increase in lymphocytes at higher work loads in the presence of propranolol suggests that catecholamines affect the lymphocyte count over and above their effect on cardiac output.     

Sex differences of hematological and biochemical parameters in healthy rainbow trout (Salmo gairdneri, R)

A hematological study of the rainbow trout has permitted to establish a sexual difference in the parameters related to it, such as haemoglobin, haematocrit, erythrocyte and leukocyte count. The types of leukocytes were homologated to the human blood. Haemoglobin, haematocrit, erythrocyte sedimentation rate, erythrocyte and leukocyte count values were lower in female than male. The normal values of some biochemistry parameters were equally studied and in some cases they similarly showed a sexual difference. Creatinine, triglycerides, phosphatase alkaline, sodium and globulin values were higher in female than male. Establishing a sexual difference from the biochemical and hematological parameters is possible.     

Electron microscopy for the diagnosis of tumours.

The role of leukocyte transfusions in the prevention and treatment of infections in adults with granulocytopenia was investigated. Leukocytes were obtained from healthy volunteers by continuous-flow centrifugation. Histocompatibility antigen (HLA)-matched leukocytes were used to assess the prophylactic value of leukocyte transfusions. Seven patients with acute myelogenous leukemia received HLA-matched leukocytes during the period of maximal granulocytopenia associated with initial remission induction therapy; 20 concurrently treated patients who did not receive leukocyte transfusions were the control group. The patients receiving HLA-matched leukocytes had significantly fewer (P = 0.043) infectious episodes (not bacteriologically proven) during the study period, and remission occurred in 5 of the 7, compared with 10 of the 20 controls. In addition, 52 series of two or more ABO-compatible transfusions were given to 50 patients with proven infection or elevated temperature presumed due to infection and a granulocyte count of less than 0.5 X 10(9)/L. Response, indicated by a decrease in temperature, occurred in 23 patients. Leukocyte transfusions thus have an important adjuvant role in the management of patients with severe granulocytopenia.     

Leukocytic shifts following pancreatic resection with a plasma scalpel and cryodestruction]

Two series of experiments were carried out on dogs. In the first series, blood leukocytes count was studied after resection of the pancreas using plasma scalpel. The resection caused two-phase leukocyte reaction: neutrocytosis (phase I) and leukocytosis involving mainly lymphocytes and monocytes (phase II). During the first 24 hours after the resection, a sharp increase of the leukocyte intoxication index (LII) was observed. The second series of experiments was performed using the combination of plasma scalpel and cryodestruction. The graphic curves denoted a sharp fall both in total leukocytic counts and in the different types of leukocytes which were plotted separately (neutrophils, eosinophils, etc.) This can be explained by the absence of the second (lympho-monocyte) reaction. Only a slight increase in LII occurred. These results reflect lower degree of the protection and adaptation reactions of leukocytes, this being in favor of a combination of plasma scalpel and cryodestruction during the operation.     

Leukocyte – endothelial interactions in inflammation

At sites of inflammation, infection or vascular injury local proinflammatory or pathogen-derived stimuli render the luminal vascular endothelial surface attractive for leukocytes. This innate immunity response consists of a well-defined and regulated multi-step cascade involving consecutive steps of adhesive interactions between the leukocytes and the endothelium. During the initial contact with the activated endothelium leukocytes roll along the endothelium via a loose bond which is mediated by selectins. Subsequently, leukocytes are activated by chemokines presented on the luminal endothelial surface, which results in the activation of leukocyte integrins and the firm leukocyte arrest on the endothelium. After their firm adhesion, leukocytes make use of two transmigration processes to pass the endothelial barrier, the transcellular route through the endothelial cell body or the paracellular route through the endothelial junctions. In addition, further circulating cells, such as platelets arrive early at sites of inflammation contributing to both coagulation and to the immune response in parts by facilitating leukocyte–endothelial interactions. Platelets have thereby been implicated in several inflammatory pathologies. This review summarizes the major mechanisms and molecules involved in leukocyte–endothelial and leukocyte-platelet interactions in inflammation.     

Letter: Limited licensure.

We examined the relationship of leukocyte colony-stimulating activity (CSA) in vitro to neutrophil count in vivo. Using a standard two-layer system, cultures of 10⁶ leukocytes were assayed for their ability to stimulate colony formation by human bone marrow colony-forming cells. The total leukocyte CSA per ml (TLCSA) of blood varied directly with the blood neutrophil count in a group of patients with a wide range in blood neutrophil count, and in two patients recovering from neutropenia in whom serial observations were made. In the latter two patients the rise in TLCSA did not antedate the rise in blood neutrophil count, suggesting that blood leukocyte colony-stimulating factor (CSF) per se probably has little biologic significance. However, release into the circulation of cells which generate CSF could be an important way of controlling the amount of CSF acting within the marrow. In one patient the CSA of dialyzed serum increased after the rise in TLCSA, while undialyzed serum contained no CSA.     

Comparative suitability of CFDA‐SE and rhodamine 6G for in vivo assessment of leukocyte‐endothelium interactions

Intravital fluorescence microscopy (IVM) is a predestined tool for investigating the fate of leukocytes during the process of leukocyte recruitment. In the present study, the commonly used dye for this purpose, rhodamine 6G, and carboxyfluorescein diacetate succinimidyl ester (CFDA‐SE) were compared for leukocytes labelling with respect to suitability for IVM studies. Their potential in labelling different leukocytes subpopulations as well as their fluorescence intensities were assessed by flow cytometry revealing distinct differences between both dyes. These differences had a profound impact on their application for in vivo imaging of leukocyte‐endothelium interactions. In summary, CFDA‐SE revealed superior in labelling leukocytes for in vivo microscopy with respect to image quality. In addition, we could show the efficiency of CFDA‐SE also under disease condition in an animal model of sepsis. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The fluid shear stress distribution on the membrane of leukocytes in the microcirculation

Recent in-vivo and in-vitro evidence indicates that fluid shear stress on the membrane of leukocytes has a powerful control over several aspects of their cell function. This evidence raises a question about the magnitude of the fluid shear stress on leukocytes in the circulation. The flow of plasma on the surface of a leukocyte at a very low Reynolds number is governed by the Stokes equation for the motion of a Newtonian fluid. We numerically estimated the distribution of fluid shear stress on a leukocyte membrane in a microvessel for the cases when the leukocyte is freely suspended, as well as rolling along or attached to a microvessel wall. The results indicate that the fluid shear stress distribution on the leukocyte membrane is nonuniform with a sharp increase when the leukocyte makes membrane attachment to the microvessel wall. In a microvessel (10 microns diameter), the fluid shear stress on the membrane of a freely suspended leukocyte (8 microns diameter) is estimated to be several times larger than the wall shear stress exerted by the undisturbed Poiseuille flow, and increases on an adherent leukocyte up to ten times. High temporal stress gradients are present in freely suspended leukocytes in shear flow due to cell rotation, which are proportional to the local shear rate. In comparison, the temporal stress gradients are reduced on the membrane of leukocytes that are rolling or firmly adhered to the endothelium. High temporal gradients of shear stress are also present on the endothelial wall. At a plasma viscosity of 1 cPoise, the peak shear stresses for suspended and adherent leukocytes are of the order of 10 dyn/cm2 and 100 dyn/cm2, respectively.     

Exercise training prevents the inflammatory response to hypoxia in cremaster venules.

Systemic hypoxia produces microvascular inflammation in several tissues, including skeletal muscle. Exercise training (ET) has been shown to reduce the inflammatory component of several diseases. Alternatively, ET could influence hypoxia-induced inflammation by improving tissue oxygenation or increasing mechanical antiadhesive forces at the leukocyte-endothelial interface. The effect of 5 wk of treadmill ET on hypoxia-induced microvascular inflammation was studied in the cremaster microcirculation of rats using intravital microscopy. In untrained rats, hypoxia (arterial Po(2) = 32.3 +/- 2.1 Torr) increased leukocyte-endothelial adherence from 2.3 +/- 0.4 to 10.2 +/- 0.3 leukocytes per 100 microm of venule (P < 0.05) and was accompanied by extravasation of FITC-labeled albumin after 4 h of hypoxia (extra-/intravascular fluorescence intensity ratio = 0.50 +/- 0.07). These responses were attenuated in ET (leukocyte adherence was 1.5 +/- 0.4 during normoxia and 1.8 +/- 0.7 leukocytes per 100 mum venule after 10 min of hypoxia; extra-/intravascular fluorescence intensity ratio = 0.11 +/- 0.02; P < 0.05 vs. untrained) despite similar reductions of arterial (32.4 +/- 1.8 Torr) and microvascular Po(2) (measured with an oxyphor-quenching method) in both groups. Shear rate decreased during hypoxia to similar extents in ET and untrained rats. In addition, circulating blood leukocyte count was similar in ET and untrained rats. The effects of ET on hypoxia-induced leukocyte-endothelial adherence remained up to 4 wk after discontinuing training. Thus ET attenuated hypoxia-induced inflammation despite similar effects of hypoxia on tissue Po(2), venular shear rate, and circulating leukocyte count.     

The guidance receptor neogenin promotes pulmonary inflammation during lung injury

Lung injury is marked by a persistent self-propagating inflammation within the pulmonary tissue that is initiated by the migration of leukocytes into the alveolar space. Recent work has demonstrated that neuronal guidance proteins are involved into the orchestration of leukocyte migration. Neogenin is a crucial guidance receptor for axonal migration, yet its role during leukocyte migration and acute inflammation is to date unknown. Here, we report that neogenin influences neutrophil migration across endothelial HMEC-1 and alveolar A549 monolayers in vitro. In vivo, Neo1(-/-) mice demonstrated 59% reduced cell count, 41% reduced TNF-α, and 76% reduced IL-6 levels within the alveolar space during lung injury. In studies employing chimeric animals, the presence of Neo1(-/-) bone marrow was associated with a 42% reduction of cell count and reduced inflammatory changes within pulmonary tissue during lung injury. The functional inhibition of neogenin through antibody injection confirmed these results and the role of neogenin for the inflammatory changes within the alveolar space. Previously unappreciated, the guidance receptor neogenin has a significant effect on the orchestration of leukocyte migration and the control of acute inflammation.     

Determination of the glycogen content in single neutrophil leukocytes using a micromodel of leukocyte glycogen.

The kinetics of the periodic acid oxidation as part of the periodic acid-Schiff reaction was studied by combined microinterferometry and microspectrophotometry in micromodel systems of liver glycogen and leukocyte glycogen as well as in neutrophil leukocytes. The initial formation of Schiff-positive chromogens was more rapid in neutrophil leukocytes than in liver or leukocyte glycogen. The chromogen formation was, however, practically complete within 60 min in both neutrophil leukocytes and leukocyte glycogen, but this did not appear to be the case in liver glycogen. Differences in the rate of chromogen formation may depend on various factors such as differences in the source and treatment of the glycogen. The complete periodic acid-Schiff reaction appears to be a measure of the glycogen amount in neutrophil leukocytes and the microdroplet system of leukocyte glycogen is considered to be an appropriate model for the estimation of the glycogen amount in single neutrophil leukocytes. A mean value of 13.3 10-12 g glycogen per normal human neutrophil was found.     

Effect of intrarenal infusion of synthetic PAF-acether in dogs

The effect of intrarenal infusion of PAF-acether was studied in dogs. PAF-acether infusions caused a dose-dependent decrease in glomerular filtration rate, renal blood flow and urinary flow and electrolyte excretion, without significant changes in mean arterial pressures. In addition, the higher doses used caused also increases in packed cell volume, and decreases in plasma proteins and leukocyte and platelet count, whereas the lower doses did not elicit those changes. These data suggest that PAF-acether causes an impairment in renal function which is in part mediated by vasoactive substances released from platelets and leukocytes.     

Sensitive and accurate quantification of human leukocyte migration using high-content Discovery-1 imaging system and ATPlite assay

Migration is a fundamental aspect of leukocyte behavior and represents a significant therapeutic target clinically. However, most migration assays used in research are relatively low throughput and not easily compatible with rapid analysis or high-throughput screening (HTS) protocols required for drug screening assays. We therefore investigated the quantification of the migration of human leukocytes using the Molecular Devices high-content Discovery-1 platform or PerkinElmer ATPlite assay compared to manual counting. We have conducted extensive assay validation, investigating the detection limits, sensitivity, and precision of each method to count human leukocytes. Leukocyte migration assays were conducted using 96-well HTS-Transwell plates and the potent chemokine stromal cell-derived factor-1 (SDF-1). We reveal that the Discovery-1 and ATPlite methods developed here provide useful approaches to quantify leukocyte migration in an HTS manner with high levels of detection, sensitivity, and precision.     

Regulation of hydroxymethylglutaryl-CoA reductase in rat leukocytes

Methods were developed for the assay of hydroxymethylglutaryl-CoA reductase (NADPH) activity in microsomes from rat leukocytes. The activity in freshly isolated leukocytes is low compared to rat liver but can be assayed reliably. The patterns of response of leukocyte reductase in the assay to variation in substrate concentration, protein concentration, and time mimic those of rat liver reductase. Reductase activity in leukocyte microsomes, as in liver microsomes, is depressed by dietary cholesterol and by fasting and is elevated by dietary cholestyramine. Unlike liver reductase, leukocyte reductase activity does not exhibit a detectable diurnal rhythm. We conclude that the assay of reductase in freshly isolated leukocytes holds promise as a technique for detecting the effects of various factors on cholesterol synthesis in vivo.     

Enzyme release and morphological changes in leukocytes induced by mechanical trauma

Polymorphonuclear (PMN) leukocytes exposed to mechanical trauma in vitro will release enzymes both from azurophilic and specific granules at shear stress levels of between 75 and 150 dyn/cm2 for 10 min. In addition, at these shear stresses the leukocyte count in whole blood decreased only slightly and the number of ruptured leukocytes on Wright-stained blood films increased significantly. At higher shear stresses, enzyme release and leukocyte damage increased monotonically. Transmission electron microscopy evaluation of sheared PMNs revealed that remaining intact cells had minor morphological changes at stresses of 150 dyn/cm2. They were characterized by clublike cytoplasmic potrusions, spherical shape, and a circumferential distribution of cytoplasmic granules. At higher shear stresses (600 dyn/cm2) cell destruction was marked. Intact PMNs contained fewer cytoplasmic granules, a large number of vacuoles, and condensed nuclear chromatin. These studies show that PMN morphology and function are at least as sensitive to mechanical trauma as similar platelet alterations seen in other studies.     

Numerical simulation of flow characteristics in a permeable liver sinusoid with leukocytes

Double-layered channels of sinusoid lumen and Disse space separated by fenestrated liver sinusoidal endothelial cells (LSECs) endow the unique mechanical environment of the liver sinusoid network, which further guarantees its biological function. It is also known that this mechanical environment changes dramatically under liver fibrosis and cirrhosis, including the reduced plasma penetration and metabolite exchange between the two flow channels and the reduced Disse space deformability. The squeezing of leukocytes through narrow sinusoid lumen also affects the mechanical environment of liver sinusoid. To date, the detailed flow-field profile of liver sinusoid is still far from clear due to experimental limitations. It also remains elusive whether and how the varied physical properties of the pathological liver sinusoid regulate the fluid flow characteristics. Here a numerical model based on the immersed boundary method was established, and the effects of Disse space and leukocyte elasticities, endothelium permeability, and sinusoidal stenosis degree on fluid flow as well as leukocyte trafficking were specified upon a mimic liver sinusoid structure. Results showed that endothelium permeability dominantly controlled the plasma penetration velocity across the endothelium, whereas leukocyte squeezing promoted local penetration and significantly regulated wall shear stress on hepatocytes, which was strongly related to the Disse space and leukocyte deformability. Permeability and elasticity cooperatively regulated the process of leukocytes trafficking through the liver sinusoid, especially for stiffer leukocytes. This study will offer new insights into deeper understanding of the elaborate mechanical features of liver sinusoid and corresponding biological function.     

Abdominal lymphatic pump treatment increases leukocyte count and flux in thoracic duct lymph

BACKGROUND: Previous studies suggest that rhythmic compression of the abdomen (abdominal lymphatic pump techniques, LPT) enhances immunity and resistance to infectious disease, but direct evidence of this has not been documented. In this study, the thoracic duct of eight anesthetized mongrel dogs was catheterized, so the immediate effects of LPT on lymph flow and leukocyte output could be measured. METHODS AND RESULTS: Lymph flow was measured by timed collection or ultrasonic flowmeter, and lymph was collected over ice under 1) resting (baseline) conditions, and 2) during application of LPT. The baseline leukocyte count was 4.8 +/- 1.7 x 10(6) cells/ml of lymph, and LPT significantly increased leukocytes to 11.8 +/- 3.6 x 10(6) cells/ml. Flow cytometry and differential cell staining revealed that numbers of macrophages, neutrophils, total lymphocytes, T cells and B cells were similarly increased during LPT. Furthermore, LPT significantly enhanced lymph flow from 1.13 +/- 0.44 ml/min to 4.14 +/- 1.29 ml/min. Leukocyte flux, computed from the product of lymph flow and cell count, was increased by LPT from 8.2 +/- 4.1 x 10(6) to 60 +/- 25 x 10(6) total cells/min. Similar trends were observed in macrophages, neutrophils, total lymphocytes, T cells and B cells during LPT. CONCLUSIONS: LPT significantly increased both thoracic duct lymph flow and leukocyte count, so lymph leukocyte flux was markedly enhanced. Increased mobilization of immune cells is likely and important mechanism responsible for the enhanced immunity and recovery from infection of patients treated with LPT.