Introduction to the biology of phagocytosis.
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Animals↗
Biomedical subjects
M Angeles Esteban
Publications and source records attributed to M Angeles Esteban.
Are thrombocytes and platelets true phagocytes?
Thrombocytes and platelets, beyond their primary function in hemostasis, seem to play an active role in inflammation. As regards their phagocytic ability, the results to date are confusing, incomplete, and somewhat contradictory. Whereas the interaction of avian thrombocytes or mammalian platelets with bacteria both in vitro and in vivo has received wide attention, almost no information exists on the topic in "lower" vertebrates. The aim of this work is to review the available information on the phagocytic properties of thrombocytes and platelets. Particular attention is payed to the ontogeny of these cells, the soluble factors involved in the inflammatory process derived from them, and their interaction with particulate material, mainly with bacteria.
Animals↗
Lack of effect of combining different stressors on innate immune responses of seabream (Sparus aurata L.).
A complex stressful event, which commonly occurs in modern aquacultural practices, was broken down into factors that were analysed both individually and jointly to assess their effect on two stress indicators (blood glucose and serum cortisol levels) and two activities of the innate immune response (serum complement and head-kidney leukocyte respiratory burst). For this, gilthead seabream (Sparus aurata L.) specimens were exposed to the following stressors: physical disturbance, crowding, anaesthesia with 2-phenoxyethanol and air exposure. At 0, 1, 2, 3 and 4 days post-stress, blood and serum samples were collected to measure glucose concentration and cortisol and complement levels, respectively. Head-kidney leukocytes were isolated and assayed to evaluate respiratory burst activity. The results show that physical disturbance, crowding and anaesthesia produced an occasional increase in glucose and cortisol concentrations. Crowding and anaesthesia induced a depression in complement activity, while hypoxia by air exposure caused a reduction in the respiratory burst. When all factors were jointly applied both humoral and cellular defences were compromised and cortisol values remained high throughout the experimental period. Any long-term effects of this abnormal serum cortisol levels on the immune system remain unknown.
Animals↗
Oral administration of yeast, Saccharomyces cerevisiae, enhances the cellular innate immune response of gilthead seabream (Sparus aurata L.).
The effects of including lyophilised whole yeast, Saccharomyces cerevisiae, in the diet on the seabream innate immune response were investigated. Gilthead seabream (Sparus aurata L.) specimens were fed four different diets for 4 weeks: a commercial diet as control and the same diet supplemented with 1, 5 or 10 g/kg yeast. After 1, 2 and 4 weeks, serum complement titres, as a humoral parameter, and phagocytic, respiratory burst, myeloperoxidase and natural cytotoxic activities of head-kidney leucocytes, as cellular parameters, were evaluated. The results showed that yeast supplements enhanced all the latter responses, but not the humoral response. This enhancement was dose-dependent except for the cytotoxic activity that was only stimulated by the lower dose of yeast assayed. As yeast cell walls are able to enhance the seabream cellular innate immune response, these results support the possible use of whole yeast as natural inmunostimulants in common fish diets.
Adjuvants, Immunologic↗
Effect of oral administration of high vitamin C and E dosages on the gilthead seabream (Sparus aurata L.) innate immune system.
The effect of the oral administration of high dosages of vitamins C and E on the innate immune system of the seabream was investigated. Gilthead seabream (Sparus aurata L.) were fed four different diets for 45 days: a commercial diet as control, a 3g/kg vitamin C-supplemented diet, a 1.2g/kg vitamin E-supplemented diet or a diet containing both vitamin supplements. After 15, 30 and 45 days, serum ascorbic acid and alpha-tocopherol levels, growth, complement titers and head-kidney leucocyte phagocytic and respiratory burst activities were evaluated. The results showed that serum vitamin levels reflected dietary input. Fish fed the vitamin C-supplemented diet showed an enhanced respiratory burst activity, while fish fed the vitamin E-supplemented diet exhibited increased complement and phagocytic activities. All of these positive effects were found in fish fed the joint diet, as well as a synergistically enhanced respiratory burst activity at day 30. The results demonstrate that in vivo vitamins C and E exert a synergistic effect enhancing the respiratory burst activity of seabream phagocytes.
Administration, Oral↗
Cytochemical characterization of leucocytes from the seawater teleost, gilthead seabream (Sparus aurata L.).
The cytochemical characterization of head-kidney and peripheral blood leucocytes of gilthead seabream (Sparus aurata L.) was studied by light and electron microscopy. Neutrophilic granulocytes show some cytoplasmic granules, which are positive for alkaline phosphatase and peroxidase but acid phosphatase negative. The scarce granules found in the cytoplasm of the circulating neutrophils and their cytochemical features seem to be indicative of an immature stage. Acidophils are also alkaline phosphatase and peroxidase positive at pH 11.0. They are strongly positive for acid phosphatase and acid phosphatase activity may thus be considered a cytochemical marker to characterize and differentiate neutrophilic from acidophilic granulocytes in this fish species. Three granule populations are characterized in the cytoplasm of the gilthead seabream acidophils: the first is positive only for peroxidase and the second contains a dense core with acid and alkaline phosphatase activities, surrounded by a thin peroxidase positive electron-dense halo. The third granule type contains an eccentric core, which is strongly positive for acid and alkaline phosphatase and peroxidase. As regards their cytochemical features, the first and second granule types seem to correspond respectively to the azurophilic and specific granules found in acidophils of mammals and could be involved in phagocytic processes, thus playing an important microbicidal role in this species. The monocytes, monocyte-macrophages and macrophages show different cytochemical features. The first have scarce acid phosphatase-positive lysosomes, while blood monocyte-macrophages and macrophages are positive for acid and alkaline phosphatases and for peroxidase; the monocyte-macrophages show scarce lysosomes.
Animals↗
Blood cells of the gilthead seabream (Sparus aurata L.): light and electron microscopic studies.
The peripheral blood cells of the gilthead seabream (Sparus aurata L.) were studied by light and transmission and scanning electron microscopic methods. Acidophilic erythroblasts and mature erythrocytes, round, oval, and fusiform thrombocytes, neutrophils, acidophils and basophils, lymphocytes, plasma cells, and monocyte-macrophages were characterized. A comparison of our light and electron microscopic results was carried out. The results were discussed with those for other fish species and the main modifications from the common vertebrate haematological pattern observed being considered.
Animals↗