ELECTRON MICROGRAPHIC STUDIES OF PHAGOCYTIC CELLS. I. MORPHOLOGICAL CHANGES OF THE CYTOPLASM AND GRANULES OF RABBIT GRANULOCYTES ASSOCIATED WITH INGESTION OF ROUGH PNEUMOCOCCUS.
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OBJECTIVE: Vascular endothelial growth factor (VEGF) is a potent inducer of capillary permeability and its role as a crucial mediator in pleural fluid formation has been established. This study was conducted to assess the usefulness of VEGF for diagnosing malignant and non-malignant pleural effusions of various causes. PATIENTS AND METHODS: VEGF levels in pleural effusions collected from 52 patients (20 with malignant effusion, 12 with tuberculous effusion, 10 with transudative effusion, and 10 with parapneumonic effusion) were assessed by enzyme-linked immunosorbent assay. RESULTS: The median level of VEGF was significantly higher (P = .001) in exudative effusions (10.16 pg/mL) than in the transudative effusions (3.82 pg/mL). Although malignant pleural fluids tended to have higher median and mean levels of VEGF compared to tuberculous effusions, the difference was not statistically significant. Pleural VEGF levels in subtypes of lung cancer and in malignant effusions of different origins were not significantly different. CONCLUSIONS: In conclusion, although VEGF levels in pleural effusions of different origins vary, they were only able to discriminate exudates from transudates significantly in this study. Further studies in larger groups of patients are needed to establish the role of VEGF in diagnosing malignant and/or tuberculous effusions.
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Macrophages from rabbit peritoneal exudate cells incubated in vitro with T(2) bacteriophage from 10 up to 120 minutes show phage particles adsorbed to cell membranes, in the process of being engulfed by means of rhopheocytosis, micropinocytosis, and phagocytosis, and localized within dense vacuoles, semi-dense vacuoles, and clear vacuoles of the cytoplasm. The electronmicrographs suggest that newly formed endocytic vacuoles containing phage particles fuse with one another and also fuse with dense bodies of the cytoplasm as they migrate towards the cell interior, thus yielding larger vacuoles of varying densities containing higher concentrations of phage. The polymorphonuclear cells present in a small proportion in the peritoneal exudate cells also endocytosed phage particles. The T(2) particles are found in large cytoplasmic vacuoles surrounded by an electron-opaque material presumably derived from cytoplasmic granules. No disintegration of T(2) phage within the macrophage following incubations up to 120 minutes could be demonstrated; however, disrupted phage particles were noted within cytoplasmic vacuoles of polymorphonuclear leucocytes after 15 minutes' incubation.
Peritoneal exudate cells from animals exhibiting delayed hypersensitivity are inhibited from migrating in vitro by specific antigen. This inhibition is completely abolished by pretreatment of the sensitive cells with trypsin. The action of trypsin is prevented by soybean trypsin inhibitor. The results of experiments with mixtures of normal and sensitive cells suggest that trypsin alters an immunologic capacity of the sensitive cells. Trypsinized sensitive cells are capable of passively transferring delayed hypersensitivity and peritoneal cells taken from recipient animals are inhibited from migrating in vitro by specific antigen. These results suggest that the cells rapidly resynthesize the material removed by trypsin. The possible nature of the material removed by trypsin is discussed.
The anti-inflammatory effect of various substances was measured in rats implanted with cotton wool pellets. Injection or implantation of irritant materials decreased the deposition of granulation tissue on the pellets. As the amount of irritant material increased there was a corresponding decrease in the amount of tissue deposited on the pellets. There is evidence that this could not be explained by a limit to the amount of granulation tissue available within the body, and competition for it between the cotton pellets and the implanted substances. An alternative hypothesis that an anti-inflammatory substance is produced at the site of irritation (the site of implantation of the irritant substance, such as polyester sponges) was investigated. The evidence obtained supports this hypothesis. Inflammatory exudate, squeezed from polyester sponges which had been implanted subcutaneously in the backs of adrenalectomized rats. The substance responsible for this effect is probably not a steroid, and is not normally present in the plasma of adrenalectomized animals. There is, however, some (although not conclusive) evidence that it is present in the plasma of animals in which sponges have been implanted. It does not appear to be produced by incubation in vitro of plasma with sponge. The significance of these observations is discussed.
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