Plasma membrane potential interferes with the respiratory burst of peripheral granulocytes

Membrane potential is involved in the regulation of several immune functions developed by granulocytes. The Na⁺/K⁺ gradient across the plasma membrane, mainly generated by the Na⁺/K⁺ pump, plays a key role in the maintenance of membrane potential. This study is focused on the correlation between plasma membrane potential and the in vitro receptor - triggered respiratory burst of normal human peripheral granulocytes. The respiratory burst was measured as superoxide anion release by the cytochrome c reduction test and plasma membrane potential was modulated by experimental changes of the extracellular potassium concentration. Results show a differentiated cellular response, depending on the in vivo activation state and on the signals received in vitro by granulocytes via CR3 or FcγR. Alteration of the membrane potassium gradient modulates the respiratory burst of unstimulated and CR3-activated cells, whilst it does not seem to significantly interfere with the signals delivered by FcγR.     

Beta-endorphin in granulocytes

The literature indicates that beta-endorphin can be found in the mononuclear cells of peripheral blood. In the present experiments the endorphin content of granulocytes was studied, compared to lymphocytes as reference cells. Granulocytes as well, as lymphocytes contain endorphin. The granulocytes' endorphin content is much higher. Both lymphocytes and granulocytes are also able to take up endorphin from the milieu.     

Der Mengen- und Spurenelementgehalt des Rinderhaares als Indikator der Calcium-, Magnesium-, Phosphor-, Kalium-, Natrium-, Eisen-, Zink-, Mangan-, Kupfer-, Molybdän- und Kobaltversorgung

Many health effects can be attributed to the Mediterranean herb oregano (Origanum vulgare L.) and several studies demonstrated the improving effect on performance, changes in blood count, antibacterial, antifungal and immunmodulating abilities. The majority of these investigations were carried out with processed essential oil, while whole plant material was only used in a few studies. Thus, the aim of the present experiment was to test the effect of increasing proportions of dried oregano in piglet feed on health and performance, with a special focus on immune modulation. A total of 80 male castrated weaned piglets (body weight [BW] 7.9 kg ±1.0 kg) were used in a feeding experiment lasting 5 weeks. They were assigned to 4 experimental groups: a control diet, and three diets with an oregano supplementation at 2 g, 4 g and 8 g per kg feed, respectively, corresponding to 23.5 mg, 46.9 mg and 93.9 mg carvacrol/kg DM. After 3 weeks, half of each group was challenged with 5 µg lipopolysaccharides (LPS) per kg BW. Blood samples were collected 2 h after LPS stimulation and analysed for T-cell phenotypes, granulocyte activity, clinical-chemistry as well as white and red blood count. The results indicate no effects of oregano on performance. In contrast, oregano altered the lymphocyte proportion and the ratio of CD4⁺ and CD8⁺ T-cells as well as the triglyceride concentration in the serum of non-stimulated and in LPS-stimulated piglets. In conclusion, whole plant supplementation of oregano to piglet feed altered immune-related parameters, but did not modulate the acute inflammatory response induced by LPS stimulation.     

Effect of Hypothalamic Proline-Rich Peptide (PRP-1) on Neuronal and Bone Marrow Cell Apoptosis

The AGAPEPAEPAQPGVY proline-rich peptide (PRP-1) was isolated from neurosecretory granules of the bovine neurohypophysis; it is produced by N. supraopticus and N. paraventricularis. It has been shown that PRP-1 has many potentially beneficial biological effects including immunoregulatory, hematopoietic, antimicrobial and anti-neurodegenerative properties. Here we investigated the influence of PRP-1 on staurosporine-induced apoptosis of postnatal hippocampal cells and on doxorubicin-induced bone marrow granulocyte- and monocyte apoptosis. The intention was to further characterize the effect of PRP-1 on the survival rate of neurons and in context with myelopoiesis. We demonstrate that PRP-1 significantly reduced apoptosis of postnatal hippocampal cells induced by staurosporine. The protective effect of PRP-1 against apoptotic cell death was shown to be both time- and dose-dependent. Neuroprotection was more pronounced after prolonged pretreatment of the cells with PRP-1 before the induction of apoptosis with staurosporine. The related peptide [arg⁸]vasopressin did not reveal neuroprotection. PRP-1 also significantly reduced apoptosis of bone marrow monocytes and granulocytes induced by doxorubicin. This protective effect lasted for 2-4 h and was not detectable anymore after 24 h when PRP-1 and doxorubicin were added simultaneously. Previously obtained data and results of the current studies suggested that the hypothalamic PRP-1 possibly represents an endogenous peptide whose primary functions are to regulate myelopoiesis and neuron survival as we provide evidence that PRP can differentially reduce both staurosporine- and doxorubicin-induced hippocampal and bone marrow cell apoptosis.     

Phagocytosis by carp granulocytes; in vivo and in vitro observations

The phagocytic ability of carp (Cyprinus carpio L.) granulocytes was evaluated in vivo and in vitro. In suspensions of head kidney cells, neutrophil granulocytes incorporated both latex beads and coccidian merozoites. In intestinal tissues from carp with a Goussia carpelli infection, all granulocyte cell types (neutrophils and cells of the basophilic-eosinophilic complex) phagocytosed cell detritus and coccidian developmental stages, mainly merozoites.     

Schistosoma mansoni: Inhibition in vitro of granulocyte cytotoxicity against schistosomula by autologous mononuclear cells from patients

Granulocytes and mononuclear cells from normal subjects are able to kill Schistosoma mansoni schistosomula in the presence of human complement in vitro. In contrast, mononuclear cells from chronic schistosomiasis patients failed to kill the parasites. The relative efficiencies expressed in terms of the mean percentage killing of schistosomula for 15 experiments were 50.5 ± 3.2 and 49.7 ± 3.5 for granulocytes from normal and infected patients, and 50.8 ± 2.8 against 23.0 ± 3.2 for mononuclear cells from normal and infected patients, respectively. The killing effect of granulocytes dropped from 48.7 ± 2.8 to 22.1 ± 2.2 when autologous mononuclear cells from chronically infected patients were added to the system. Similar inhibitory effect of granulocyte function was obtained when these cells were incubated with normal mononuclear cells precultured with concanavalin A. Extracts prepared from mononuclear cells obtained from infected patients had the same inhibitory effect of intact cells on the complement-dependent granulocyte cytotoxicity.     

Cellular immune responses of spruce budworm larvae to Entomophthora egressa protoplasts and other test particles

The protoplast stage of two isolates of Entomophthora egressa developed normally and eventually produced conidiophores when injected into larvae of the spruce budworm, Choristoneura fumiferana. The spruce budworm hemocytes never made long-term contact with the protoplasts either in vivo or in vitro. The protoplasts made active, short-term contact with spruce budworm granulocytes both in vivo and in vitro. Total larval hemocyte counts (THC) initially declined when larvae were injected with protoplasts, growth medium (MGM), or Escherichia coli. The recovery rate to THC control levels was similar for MGM and protoplasts and supports the concept of nonrecognition of protoplasts by the hemocytes. The granulocytes were important in both nodulation and phagocytosis of E. coli and Bacillus cereus, whereas the plasmatocytes were important in phagocytosis. In in vitro studies, spruce budworm granulocytes did not adhere to rod-shaped hyphal bodies, spherical hyphal bodies, or germinating spherical hyphal bodies of E. egressa, whereas the granulocytes readily encapsulated the hyphae. There was no evidence for the production by the protoplasts of metabolites which might interfere with hemocyte adhesion. When protoplasts contacted Tenebrio molitor granulocytes, the protoplasts reacted by increasing the number of protoplasmic extensions and by granule discharge. The process of granule discharge may be an active protoplast defense mechanism. The sporangiospores of Absidia repens and Rhizopus nigricans adhered to spruce budworm granulocytes; however, the number of A. repens spores per granulocyte and the level of granulocytes with spores decreased in the presence of phenylthiourea. The adhesion of A. repens spores to granulocytes was enhanced by N-acetylglucosamine, whereas glucosamine, sucrose, fucose, fructose, arabinose, and galactose either had no effect on or reduced spore adhesion. Thus, the chitin (or its subunits) in the hyphal wall may initiate the granulocyte response.     

Eosinophilic granulocytes in the epidermis of Oreochromis mossambicus gill filaments studied in situ

Granular cells were observed in the epidermis of isolated gill filaments using Normaski microscopy at×400 magnification. Granulocytes were motile and chemotactic to histamine (introduced via a micropipette into the filament) and to the products of degranulation of neighbouring granulocytes within the epidermis. The abundance of visible granulocytes within the epidermis of gill filaments was increased in the period following net capture, confirming their migratory ability. Cells isolated from gill tissue are poorly glass adherent. They are also eosinophilic and more dense than macrophages and lymphocytes on a discontinuous percoll gradient. They are identified as eosinophils on the basis of these characteristics.     

A study of the surface proteins of Entomophthora egressa protoplasts and of larval spruce budworm hemocytes

Entomophthora egressa protoplasts either exposed to or not exposed to trypsin were not attacked by either trypsinized or non-trypsinized larval spruce budworm granulocytes. Granulocytes adhered to protoplasts exposed to papain, and this adhesion could be prevented by papainizing the hemocytes. Differences were observed in the responses of two E. egressa isolates when exposed to papain or to the papain-control solutions. Exposure of hemocytes to trypsin did not reduce either the number of Absidia repens sporangiospores per granulocyte or the percentage of granulocytes with spores, whereas, exposure to papain did. The role of surface proteins, particularly glycoproteins, in hemocyte-fungal cell interactions is briefly discussed.