A new method for rapid technetium-99m labelling of leucocytes: functional cell studies in vitro

The aim of this study was to assess the cytotoxicity of a new leucocyte-labelling method, which may be used clinically to localize inflammatory and immune reactions. Human blood leucocytes, their mononuclear sub-population, and mouse mononuclear bone marrow cells were labelled with 99mTc for 30-45 min, washed once, and then evaluated in various functional assays. The new procedure includes [99mTc]-labelling with a bisalt method, in the presence of dihydroxybenzoic acid as an intermediate antioxidant-complexing stabilizer, and a carboxylic acid salt of stannous ions as a reducing agent. To challenge the method, cells were labelled about two orders of magnitude more heavily in these initial methodological studies than in on-going clinical trials. Labelled leucocytes ingested latex beads as readily as the controls, but migrated chemotactically and randomly somewhat slower than the control cells. The lymphocytes were triggered by PHA and Con A in a normal way. However, lymphocytes and haemopoietic progenitor cells exposed to radiation for several days, were killed by the isotope doses used, of which about 2% (i.e. 20 MBq) were bound per million cells. All deleterious effects were apparently due to irradiation, and the labelling procedure itself did not damage the cells.

Histological alterations in the fetal mouse cerebellum after neutron irradiation: a light and electron microscopic study

Histological effects of in utero neutron irradiation (0.5 Gy) were investigated in fetal mouse cerebellum. Irradiation was performed on the 18th embryonic day. Histological alterations were examined at 2, 6 and 12 h after irradiation. The effect was most pronounced in the EGL, 6 h after irradiation. In some cells (about 24%) karyopycnosis, destruction of cytoplasmic organelles and shrinkage were observed. Remnants of destroyed cells--the pycnotic nuclei with some cytoplasmic debris around them--were rapidly phagocytized by the surrounding cells. In addition to glial elements, the EGL germinal cells also showed phagocytic activity. Dense particles appearing light-microscopically as pycnotic nuclei, proved to be mostly remnants of destroyed, phagocytized cells under electron microscope.

[Nature of the changes in the morphofunctional and cytochemical indices of blood leukocytes as affected by low-intensity microwaves]

A study was made of morphological composition of blood leukocytes, phagocytic activity, glycogen and alkaline phosphatase content of neutrophils of animals exposed to microwaves of low intensity (1-500 mu W/cm2) generated continuously (2375 MHz) and by impulses (9400 MHz). The direction of the change in these indices and rate of the postirradiation recovery was shown to depend upon intensity and duration (30-120 days) of exposure. The response of albino rats and guinea pigs to the effect of microwaves was different. The effect of microwaves of the intensities under study on the mammalian organism was assessed.

Enhanced activity of the macrophage-like cell line J774.1 following exposure to gamma radiation

Exposure of the macrophage-like cell line J774.1 to 20 gray of cobalt-60 gamma radiation resulted in a block of tritiated thymidine incorporation, along with an increase in cell "activation," as assessed by increases in lysosomal enzyme and ectoenzyme content, PMA-induced H2O2 production, and NBT staining, ingestion of E(IgG), spreading, and membrane ruffling. These changes are evident within 1 day postradiation and peak at 4 days postradiation.

[Efficacy of the paramunity inducers PIND-AVI and PIND-ORF as radioprotective agents]

A significant reduction of mortality after lethal irradiation (7,8 and 9 Gy X-ray total-body irradiation) was achieved by continuous therapeutic subcutaneous application of the biologic inducers PIND-AVI and PIND-ORF. This was obtained by a stimulation of the investigated spleen parameters and a stimulation of leucocytes and phagocytosis. The inducers had no significant influence on the radiogenic reduction of blood cells and bone marrow cells, of the relative spleen and thymus weight and of the DNA and protein level of spleen and thymus. The regeneration of blood leucocytes (preponderantly by PIND-AVI) and of the spleen (preponderantly by PIND-ORF) was accelerated, but not the thymus regeneration which was already rather low. The leucocyte phagocytosis which increased generally after irradiation was markedly stimulated by paramunization. This stimulation was also observed after a latent time in animals submitted to sham irradiation. Its temporal appearance and its quantitative and qualitative properties corresponded to the effects of inducers after X-ray irradiation. Both inducers were found to be harmless in all experiments.

Modulation of mammalian immunity by electromagnetic radiation

There have been reports that electromagnetic radiation (EMR) alters the function of the immune system; however, these reports are often contradictory. This review reexamines the literature and attempts to evaluate the data on potential mechanisms of interaction of EMR on mammalian immune function. This report concludes that there is no convincing evidence that EMR effects on the human immune system are a health hazard. It was suggested by some authors that long-term EMR exposure may impair immune surveillance, and hypothetically thus facilitate tumor growth. Additional research is needed to prove or disprove this hypothesis. Available data indicate that EMR exposure does not affect the ability of cells of the immune system to respond to a subsequent challenge. However, the time-course and magnitude of the response may be affected by exposure following stimulation. Research to date provided evidence that at least at some frequencies and/or amplitude and pulse modulations, the site of primary interaction of EMR is at the cell membrane. However, it was shown that one specific response, the increase in B complement-receptor positive lymphocytes (Cr+) in the mouse is under genetic control by a single gene localized on chromosome 5. It is suggested that cells of the immune system are a convenient model for further studies on mechanisms of EMR interaction with living systems. Future research should be directed at exploring beneficial medical applications of EMR modulation of immune responses.

[111In]oxine labelling of polymorphonuclear leucocytes: doubts concerning elution and effects on cell behaviour

Polymorphonuclear leucocytes (PMN) from normal human subjects were labelled with [111In]oxine (20 muCi 10(8) cells). In the presence of 20% autologous serum (AS), dissociation of 111In from the cells resulted in mean losses of radioactivity of 13% at 3 h and 30% at 24 h. Adherence of 111In-labelled PMN to cultured porcine endothelial monolayers was increased by 40.7 +/- 31.6% after 60 min incubation in 20% AS at 37 degrees C when compared with unlabelled cells. Phagocytosis and intracellular killing of Candida albicans were unaltered by labelling. Elution of 111In from labelled PMN together with enhanced adhesiveness may have important implications for the study of PMN kinetics and the investigation of inflammatory disease.

Viability and phagocytosis of neutrophils exposed in vitro to 100-MHz radiofrequency radiation

Rabbit polymorphonuclear leucocytes (PMN, neutrophils) obtained from peritoneal exudate were exposed in vitro for one-half or one hour to continuous wave or amplitude-modulated (20-Hz) 100-MHz RF radiation in a temperature-controlled coaxial exposure chamber at field strengths from 2.5 to 4.1 V/cm (SARs of 120 to 341 W/kg). RF exposure at 37 +/- 0.2 degrees C had no detectable effect on PMN viability or phagocytosis compared to sham-exposed cells simultaneously subjected to the same time-temperature regime. Temperature control studies indicated that at 37 degrees C no effect on PMN viability would be expected but phagocytosis would be reduced by approximately 6%/degrees C temperature increase. The absence of an effect of RF exposure suggests that there was minimal undetected intrasample heating and that phagocytosis was not affected by 100-MHz RF radiation under the conditions of this study.

The biomedical effects of laser application

This paper briefly reviews the authors' experimental and clinical use of lasers over a 20-year period, during which laser effects on 15 biological systems were studied. Low-energy laser radiation was found to have a stimulating effect on cells, and high-energy radiation had an inhibiting effect. The application of lasers to stimulate wound healing in cases of nonhealing ulcers is recommended.

[Effect of irradiation on proteins and phagocytic activity of rat blood leukocytes]

The method of chromatography on DEAE-cellulose was used to study the effect of radiation (180.6 mC/kg) on the physicochemical properties of rat leukocyte proteins. The qualitative changes were noted in the protein spectrum of leukocytes which were indicative of the substantial changes in the cell proteins. A fraction was isolated which caused a 44% inhibition of the phagocytic activity of intact leukocytes in vitro.

Radiation effects on cultured human monocytes and on monocyte-derived macrophages

Prior to administration, leukocyte transfusions are commonly irradiated with up to 5,000 R to eliminate lymphocytes and thereby prevent graft-versus-host disease in the recipient. It has been widely believed that phagocytes are resistant to this irradiation. In a recent report, we noted that phagocyte oxidative metabolism was compromised during preparation of white cells for transfusion. As part of our effort to examine the basis for this inhibition of phagocyte function during white cell preparation, we assessed the effects of irradiation on the long-lived monocytes that have been shown to persist at inflammatory foci posttransfusion. Human monocytes were irradiated for up to 3 min, receiving 2,500-5,000 R. This irradiation damaged human monocytes, significantly decreasing their in vitro survival for the first 3 wk of culture (p less than 0.02, irradiated versus control survival), and growth as assessed by two-dimensional cell size measurements during the first 2 wk of culture (p less than 0.01, irradiated versus control growth). Despite smaller cell size, total cell protein was significantly increased over time in irradiated cultures (p less than 0.001, irradiated versus control total protein per cell). Extracellular release of lysozyme and beta-glucuronidase per cell was not affected by irradiation, but extracellular lactate dehydrogenase (LDH) release was significantly increased after irradiation (p less than 0.001, irradiated versus control LDH release). Irradiated monocytes killed Listeria monocytogenes at a slower rate than the nonirradiated controls (p less than 0.05, irradiated versus control rate of killing). Thus, the data indicate that irradiation in doses used to prevent graft-versus-host disease in leukocyte transfusion recipients has a deleterious effect on in vitro human monocyte survival and function.

Defective Fc-mediated phagocytosis in gamma-irradiated mouse peritoneal macrophages

Ingestion of bovine red blood cells opsonized with IgG, by irradiated and control cultures of mouse peritoneal macrophages, was monitored at various times following exposure to 7.5-20 Gy of 60Co. Radiation produced decreases in the percentage of phagocytic cells and reduced the phagocytic index of the macrophages at 6-10 days post-irradiation. Only a small decrease in the phagocytic index of irradiated cultures was noted on day 3 post-irradiation. Cell survival as monitored by cell number and lactic dehydrogenase release as well as the levels of beta-glucuronidase and lysozyme were less sensitive to radiation exposure than was the phagocytic ability of the cultures. Addition of 8-bromo-3',5'-cyclic adenosine monophosphate and prostaglandin E2 to cultures increased the phagocytic ability of both irradiated and control cultures but did not abolish the deficit produced by radiation. The data indicate that in vitro radiation exposure produces time-dependent changes in the ability of mouse peritoneal cells to ingest IgG coated red blood cells.

Modification of autophagic degradation by medium- and illumination conditions in frog visual cells in vitro

In vertebrate visual cells, cytoplasmic organelles are degraded within autophagic vacuoles occurring in inner segments. In isolated frog retinas in vitro, an increase of autophagic activity as compared to in vivo controls was observed and a reduction of autophagic activity in dim red light as compared to bright white light (Remé, 1981). In this study, isolated frog retinas were superfused: (a) with and without serum addition to the superfusion medium at 400 1 X illumination; (b) without serum at 400 1 X fluorescent light or without visible light. Autophagy was significantly decreased, in cones more than in rods, in retinas superfused with serum containing medium and superfused without visible light. The increased autophagy in serum free medium is interpreted to provide precursor molecules for protein synthesis. The reduction of autophagy in darkness may reflect different functional and metabolic states of visual cells.

Preservation of retinal function in the RCS rat by laser treatment

The Royal College of Surgeons (RCS) rats have been used as a model for human retinitis pigmentosa. Studies on these animals have shown that the degeneration of the retina is associated with a buildup of debris produced by shed rod outer segment discs. It has been reported that localized laser lesions can increase phagocytosis in these rats. This study examined the effect of laser burns on the function of the retina of the RCS rats. One eye of 19-day-old RCS rats was treated with laser and the other eye used as control. The retinal function was measured by electroretinography at 5, 10, 15, 20, 25, 30, and 40 days after lesioning. The morphology of the retina was examined at 24 and 43 days after laser treatment. The results show that the retinal function in the treated eye was improved at all intervals and that this improvement was significant at 15, 20, and 25 days. Morphologic examination showed a significant reduction in debris accumulation in the area of the laser spot. However, at sites distal to the laser burns, no morphologic difference between the treated and untreated eyes was noted. It is concluded that the progress of retinal dysfunction in the RCS rats can be retarded by laser treatment.

Effect of whole-body irradiation on phagocytic activity of rat alveolar macrophages

The phagocytic activity of rat alveolar macrophages was studied in vitro for up to six weeks after whole-body gamma irradiation (7.5 Gy). Ingestion of fluorescent latex microspheres was evaluated using both microscopic examination and flow cytometric quantitation. After a transient decrease on first day post-irradiation, a slight increase in the phagocytic ability was observed from day 14 to day 28, with a maximum on day 21. From day 35 onwards, phagocytic capacities returned approximately to those of the controls. The percentage of phagocytic cells (cells having ingested one microsphere or more) increased by 75 per cent on day 21 after irradiation and the phagocytic index (percentage of phagocytic cells X the average number of ingested microspheres per cell) increased by 250 per cent while at the same time, the number of recovered alveolar cells decreased by 37 per cent. The augmentation of phagocytic capacities after irradiation was particularly characterized by an increase in the percentage of cells ingesting more than five microspheres. Flow cytometric studies showed a significant increase in mean cell size on day 21 post-irradiation. The augmentation of the phagocytic activity was not found when macrophages from control rats were incubated with serum or alveolar lavage fluid from an irradiated donor. Augmentation of phagocytic capacity was also observed after 8.5 Gy but no effect could be observed after 6.5 Gy.

The effect of X-radiation on the process of lung clearance after inhalation of bacteria labelled with 3H-thymidine

The respiratory tract is cleared very effectively from the inhaled particles by the ciliated bronchial epithelium, secretion of secretory cells, and specialized phagocytic cells. Within 4 hours about 80% of the inhaled microorganisms are destroyed in the respiratory tract. The rate of removal of the micro-organisms from the lungs and their destruction may play a very important role in preventing infection development. The aim of the present experiment was to study the adverse effect of ionizing radiation on the mechanisms involved in cleaning the lungs. Wistar rats were used for this purpose. They received a dose of 500 cGy. The irradiated animals and the control non-irradiated ones inhaled in a PIANO IV apparatus Staphylococcus epidermidis labelled with tritiated thymidine. Determining the clearance of the bacteria from the bronchial tree and pulmonary tissue an impairment of the mechanisms clearing the lungs in the irradiated group was demonstrated. The effect of radiation may be related to a damage to the alveolar macrophages which are principally responsible for destroying bacteria at the level of pulmonary alveoli. The relatively radiation-resistant ciliated epithelial bronchial cells may have their efficiency reduced owing to disturbances in mucus secretion by the secretory cells.

Cellular autophagocytosis induced by X-irradiation and vinblastine. On the origin of the segregating membranes

Autophagocytosis was induced in cultured, human glial cells by X-irradiation or exposure to vinblastine sulphate. A transmission electron microscopic investigation of the origin of the segregating membranes in the autophagic process was performed by labelling of endocytotic vacuoles and lysosomes with electron-dense marker particles (native and cationized ferritin, colloidal gold and thorium dioxide). Cytochemical demonstration of the lysosomal marker enzyme acid phosphatase and serial sectioning of the cells were also carried out. The majority of newly formed, double-membrane bounded autophagic vacuoles were devoid of markers for both lysosomes and endocytotic vacuoles. Moreover, no evidence of origin from the endoplasmic reticulum was found and the segregating membranes of this type of autophagic vacuoles were, by process of elimination, considered likely to be derived from Golgi vacuoles or, possibly, assembled de novo. Autophagy also appeared to be effected through an alternative pathway involving a lysosomal wrapping or microautophagic mechanism.

Effects of microwave exposure on the hamster immune system. II. Peritoneal macrophage function

Acute exposure to hamsters to microwave energy (2.45 GHz; 25 mW/cm2 for 60 min) resulted in activation of peritoneal macrophages that were significantly more viricidal to vaccinia virus as compared to sham-exposed or normal (minimum-handling) controls. Macrophages from microwave-exposed hamsters became activated as early as 6 h after exposure and remained activated for up to 12 days. The activation of macrophages by microwave exposure paralleled the macrophage activation after vaccinia virus immunization. Activated macrophages from vaccinia-immunized hamsters did not differ in their viricidal activity when the hamsters were microwave- or sham-exposed. Exposure for 60 min at 15 mW/cm2 did not activate the macrophages while 40 mW/cm2 exposure was harmful to some hamsters. Average maximum core temperatures in the exposed (25 mW/cm2) and sham groups were 40.5 degrees C (+/- 0.35 SD) and 38.4 degrees C (+/- 0.5 SD), respectively. In vitro heating of macrophages to 40.5 degrees C was not as effective as in vivo microwave exposure in activating macrophages to the viricidal state. Macrophages from normal, sham-exposed, and microwave-exposed hamsters were not morphologically different, and they all phagocytosed India ink particles. Moreover, immune macrophage cytotoxicity for virus-infected or noninfected target cells was not suppressed in the microwave-irradiated group (25 mW/cm2, 1 h) as compared to sham-exposed controls, indicating that peritoneal macrophages were not functionally suppressed or injured by microwave hyperthermia.

Microwaves (2,450 MHz) suppress murine natural killer cell activity

The effect of 2,450-MHz CW microwaves on natural killer (NK) cell activity and lymphocyte responsiveness to mitogen stimulation was studied in mice. Groups of mice were irradiated at power densities of 5, 15, or 30 mW/cm2 (SAR = 3.5, 10.5, and 21 W/kg respectively) for 1.5 h on 2 or 9 consecutive days. NK cell activity was determined using an in vitro 51Cr release cytotoxicity assay and an in vivo tumor-cell clearance assay. No consistent change was observed in the mitogen response of spleen cells from sham compared with irradiated mice. A significant suppression of NK cell activity measured in vitro was observed for mice irradiated at 30 mW/cm2, but not at 15 or 5 mW/cm2. A significant suppression of NK cell activity, as determined using the in vivo tumor clearance assay, was also observed at 30 mW/cm2. NK cell activity, as determined using the in vitro assay, returned to normal within 24 h following the last irradiation. Treatment of mice with hydrocortisone caused suppression of NK cell activity measured in vitro and in vivo. Paradoxically, peritoneal macrophage phagocytosis was enhanced following irradiation at 30 mW/cm2, the power density at which NK activity was suppressed. The possible role that microwave heating plays in producing these effects is discussed.