Effect of orexin-A on phagocytic activity of peritoneal macrophage in starved rats

The aim of this study was to investigate the effect of fasting-induced orexin-A (OXA) on inflammation and macrophage phagocytic activity. Fifty six male wistar rats were fasted for 36 h to stimulate OXA synthesis. In 24 rats, air pouches were induced subcutaneously in the intrascapular area. After (6 h) carrageenan injection into the pouches, the contents of the air pouches were removed. The exudate volume, protein content and cell count were measured. After the determination of fasting on inflammation, the peritoneal macrophages were collected from 32 rats to investigate the effect of fasting-induced OXA on macrophage phagocytic activity. Plasma OXA levels were markedly higher in fasted rats compared with control rats. The phagocytic capability of peritoneal macrophages was obtained as a percentage of phagocytosing macrophages and number of phagocytosed particles per cell. In spite of increased blood OXA level SB-334867, selective orexin type 1 receptor antagonist (10 mg/kg) did not change phagocytic activity of peritoneal macrophages. These findings indicate that 36 h fasting-induced OXA has no significant effect to phagocytosis of peritoneal macrophages.     

Effect of angiotensin II and losartan on the phagocytic activity of peritoneal macrophages from Balb/C mice

Angiotensin II (AII), a product of rennin-angiotensin system, exerts an important role on the function of immune system cells. In this study, the effect of AII on the phagocytic activity of mouse peritoneal macrophages was assessed. Mice peritoneal macrophages were cultured for 48 h and the influence of different concentrations of AII (10(-14) to 10(-7) M) and/or losartan, 10(-16) to 10(-6) M), an AT1 angiotensin receptor antagonist, on phagocytic activity and superoxide anion production was determined. Dimethylthiazoldiphenyltetrazolium bromide reduction and the nucleic acid content were used to assess the cvtotoxicity of losartan. A stimulatory effect on phagocytic activity (P < 0.05) was observed with 10(-13) M and 10(-12 M) AII concentrations. The addition of losartan (up to10(-14) M) to the cell cultures blocked (P < 0.001) the phagocytosis indicating the involvement of AT1 receptors. In contrast, superoxide anion production was not affected by AII or losartan. The existence of AT1 and AT2 receptors in peritoneal macrophages was demonstrated by immunofluorescence microscopy. These results support the hypothesis that AII receptors can modulate murine macrophage activity and phagocytosis, and suggest that AII may have a therapeutic role as an immunomodulatory agent in modifying the host resistance to infection.     

The effect of bilirubin on the fc receptor expression and phagocytic activity of mouse peritoneal macrophages

The effect of bilirubin on the phagocytic activity of mouse peritoneal macrophages and on the expression of Fc receptors and receptors for SRBC was studied. Intraperitoneally administered bilirubin influenced the expression of Fc receptors for IgM, IgG2B, IgA and IgE, whereas the expression of other receptors as well as the phagocytic activity of peritoneal macrophages remained unchanged. The possible mechanism of the effect of bilirubin on Fc receptors is discussed.     

Suppressive effect of streptomycin on the phagocytic activity of mouse peritoneal macrophages for Histoplasma capsulatum

Streptomycin inhibited the phagocytic activity of mouse peritoneal macrophages forHistoplasma capsulatum. The inhibitory effect was demonstrable following both in vitro and in vivo administration of drug. The observations from examination by direct smear were confirmed by culturing for viable phagocytized organisms. A simple and reproducible technique for the counting of viable phagocytized organisms was developed. Forty-eight hours in vitro treatment of macrophage cultures with 10 to 200 µg/ml of streptomycin produced a graded inhibition of phagocytic activity, minimal at 10 µg/ml and maximal at 200 µg/ml of streptomycin. The parenteral administration of streptomycin significantly reduced phagocytic activity of mouse peritoneal macrophages forH. capsulatum. Mice were treated daily with the subcutaneous injections of 5, 2.5 or 1 mg streptomycin or saline. At 7, 14, 21 and 28 days post-treatment phagocytic activity of macrophages obtained from these mice was tested. There was a progressive, dose-dependent decrease in the phagocytic activity of macrophages derived from streptomycin-treated mice.     

Ultrastructure and phagocytic activity of rat peritoneal macrophages exposed to low temperatures in vitro

Hypothermia affects various components of the immune system, leading to impaired immune resistance. To examine the in vitro effect of low temperature on the ultrastructure and phagocytic function of rat peritoneal macrophages, cells were incubated at 4, 10, 24, and 37 degrees C for 60 min. Subsequently, their ultrastructure and capacity to engulf latex particles and generate superoxide anions were evaluated. The results showed a close inverse relationship between incubation temperature and ultrastructural changes, i.e., the lower the temperature, the higher the number of altered cells. In addition, at lower temperatures the number of cells capable of phagocytosis was reduced; the cells engulfed fewer particles per cell and generated less superoxide anions. These findings may be relevant for explaining the increased susceptibility to bacterial infections under hypothermic conditions.     

Influence of termolabile enterotoxin of Enterobacter cloacae on phagocytic activity of mice peritoneal macrophages

Influence of termolabile enterotoxin (LT-enterotoxin) of Enterobacter cloacae on functional activity of mice peritoneal macrophages was studied and following combinations were used: LT-enterotoxin-producing E. cloacae, its isogenic pair--LT-enterotoxin non-producing E. cloacae, supernatantof broth culture containing LT-enterotoxin, and physiological salt solution (in control group). Data showing decrease in phagocytic and lysosomal activity, disorder in functions of hexosemonophosphate shunt enzymes in peritoneal phagocytes were obtained.     

Stimulation of the phagocytic function in guinea pig peritoneal macrophages by physical activity stress.

A study was made of all the different stages of the phagocytic function in peritoneal macrophages from male guinea pigs [3 (SD 1) months old] before, immediately after, and 24 h after being subjected to stress from physical activity (swimming until exhaustion). The early (10 min) and late (40 min) adherence to tissue substrates, chemotaxis, attachment and phagocytosis of Candida albicans, ingestion of inert particles (latex beads), and basal oxidative metabolism [measured by nitroblue tetrazolium (NBT) reduction] were significantly stimulated by the physical activity. After 24 h, late adherence, attachment capacities, and basal oxidative metabolism returned to basal values, whereas early adherence, chemotaxis, phagocytosis of cells and inert particles, and microbicidal capacity (production of superoxide anion measured by NBT reduction in presence of ingested material) remained significantly increased. The stress produced by physical activity, reflected in increased serum corticosterone values, led to a global stimulation of the phagocytic function.     

Changes in the phagocytic activity of the peritoneal macrophages of white mice caused by alcoholic intoxication

Observations made on white mice showed that doses of alcohol had a stimulating effect on the indices of macrophage acitivity (pagocytic number and phagocytic index), while longer administration of 40% ethyl alcohol solution (in doses of 0,1 ml for 21--30 days) suppressed the functional activity of macrophages. In vitro experiments in which macrophages were subjected to the action of ethyl alcohol showed that alcohol, depending on its concentration, had a direct effect on the cells of the microphage system.     

The effect of Mycoplasma arthritidis infection on the phagocytic activity of macrophages in rats and mice

The phagocytic activity of mononuclear phagocytes of A/J mice and Wistar rats was estimated by the carbon clearance test following injection of Mycoplasma arthritidis. In mice, the overall phagocytic activity was significantly increased at the end of the first week (P less than 0.0001), but the increase was marginal by the third and fourth weeks after injection. A significant increase in the relative weight of liver and spleen was observed even when phagocytic activity had returned to levels similar to those of controls (P less than 0.001). In rats, the overall phagocytic activity was significantly increased until the fourth week (P less than 0.00001). There was not, however, an increase in the relative weight of liver and spleen as observed for the mice. The results are discussed in the context of factors contributing to the pathogenic mechanisms responsible for differences in the patterns of arthritis due to mycoplasma observed in mice and rats.     

Effect of cyclophosphamide on the candidacidal activity of rabbit peritoneal macrophages

Single and repeated intravenous administration of cyclophosphamide significantly decreased the candidacidal activity of rabbit peritoneal macrophages. Using higher doses of the drug, a more pronounced decrease, persisting up to 10 d, was observed. The phagocytic index has not changed significantly 10 d after cyclophosphamide injection as compared with controls. No changes in the phagocytic activity were recorded. The decreased candidacidal activity may be one of the causes of serious microbial infections in cyclophosphamide-treated patients.     

Effect of melatonin on phagocytic activity and intracellular free calcium concentration in testicular macrophages from normal and streptozotocin-induced diabetic rats

This study examined the effect of melatonin (MLT) on in vitro phagocytosis of testicular macrophages taken from control and streptozotocin (STZ)-induced diabetic rats and the possible mechanism of its action. The phagocytic activity was measured as a number of latex beads ingested by 100 macrophages (PI, phagocytic index) in consecutive time points of the incubation. Changes in intracellular free calcium level [Ca²⁺]_i in isolated macrophages in vitro were measured with the use of ratio-image fluorescence microscopy (fluorescent dye: Fura2/AM). Phagocytic index in macrophages isolated from healthy rats was 20% higher than in those from diabetic animals. Melatonin in physiological concentration (10⁻⁷ M) significantly (p < 0.05) increased the PI in testicular macrophages from control animals (PI = 68 ± 5 with MLT compared to PI = 46 ± 7 without MLT) while no such effect was observed in the cells from diabetic rats (PI = 36 ± 23 with MLT compared to PI = 31 ± 11 without MLT). Basal [Ca²⁺]_i was significantly (p < 0.01) higher in macrophages from diabetic rats compared to control. Stimulation of both control and diabetic testicular macrophages with 10⁻⁷ M MLT resulted in a significant (p < 0.05) increase in [Ca²⁺]_i in cells incubated in 2.5 mM calcium solution while no such response was observed in calcium-free Tyrode solution. However, MLT evoked [Ca²⁺]_i response in macrophages isolated from diabetic animals was much lower than in macrophages isolated from age-matched controls and the time needed for maximal response was much longer. Lack of response in calcium-free solution suggests that extracellular calcium may be necessary to trigger MLT response and in its progression.     

Effect of nitric oxide on 1 ml: peritoneal macrophages activity in normal pregnancy in white rats

The activity of peritoneal macrophages, nitrotyrosine concentration and condition of free radical processes in normal pregnancy in white rats against the background of the introduction of donator (sodium nitrite) and inhibitor (Nw-nitro-L-arginine methyl ester) of nitric oxide was studied. During normal pregnancy in animals, nitrotyrosine concentration, the activity of free radical processes, and phagocytosis increase. With the introduction of nitric oxide donator, NO level increases and after the injection of antagonist of nitric oxide it is reduced. These changes are accompanied by increased lipid peroxidation and activation of phagocytic activity of macrophages.     

Effect of tuftsin on the activity of energy metabolism enzymes in peritoneal macrophages

Cytochemistry was used to measure the activity of succinate dehydrogenase (SOD), lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) in rat peritoneal macrophages under the action of the endogenous immunostimulant tuftcin (tre-lys-pro-arg) during phagocytosis of latex particles and at rest. Tuftcin did not affect the activity of the study enzymes in non-phagocytic cells. Elevation of the peptide concentration to 0.25 micrograms/ml and higher in phagocytic macrophages activated G-6-PDH and lowered the activity of LDH. Tuftcin did not alter the activity of SOD in phagocytic macrophages.     

The phagocytic activity of peritoneal macrophages in relation to Yersinia pestis with defective and complete Fra genes

In vitro study of phagocytosis has shown that in guinea pigs fraction 1 is conducive to the ingestion of Y. pestis by macrophages, to survival and proliferation of Y. pestis cells in these macrophages, as well as to their specific transformation leading to their increased ingestive and bactericidal activity with respect to Y. pestis. In mice the role of fraction 1 in phagocytosis has proved to be less significant.     

The influence of antibiotics on phagocytic and bacteriocidal activity of rabbit peritoneal macrophages stimulated by filtrates of cultured t-lymphocytes

The aim of the study was to determine the influence of twelve antibacterial antibiotics (various concentrations) on the activation of rabbit peritoneal macrophages. Macrophages were stimulated by filtrates of culture of lymphocytes T obtained from OVA immunized rabbits. Phagocytic activity and intracellular killing against Listeria monocytogenes were tested by fluorescence method. Penicillin G (0.4-50 mg/l), erythromycin and lincomycin (2.5-40 mg/l) used at all concentrations, were not exerting significant effects on activation of peritoneal macrophages. Cephalosporins, aminoglycosides, and rifampicin at low concentrations (0.4-5.0 mg/l) had no influence on phagocytosis and intracellular killing, also. Cephalosporins at concentration 10 mg/l (cephradine and cefamandole) and 50 mg/l (cefotaxime) inhibited intracellular killing and phagocytic activity. The same results were observed with ampicillin and ticarcillin (50 mg/l). The highest suppression effect was demonstrated using rifampicin at concentration 10 mg/l or more. Gentamicin, streptomycin and amicacin at concentrations 40 mg/l or more significantly inhibited macrophage activation in response to filtrates lymphocytes of culture. These inhibitions were more marked with gentamicin (10 mg/l) than amicacin (20 mg/l) or streptomycin (40 mg/l). All antibiotics did not stimulated the activity of peritoneal macrophages. The suppression activity of peritoneal macrophages by some antibiotics probably acts at the level of specific immune system by interfering with cytokine production.     

The role of macrophages in mediating the immunostimulating effects of low-frequency ultrasound

The action of low-frequency ultrasound on the body has been shown to lead to the stimulation of specific immune response, as well as immunological memory cells. The effects of low-frequency ultrasound are seemingly realized through the macrophage system of immunity, i. e. the action of ultrasound leads to the stimulation of the functional activity of macrophages, their metabolism, while blocking the macrophage system of immunity with carraginal abolishing the effects of ultrasound.     

Effect of the monooxygenase activity inhibitor ketoconazole on cholesterol esterification in mouse peritoneal macrophages

In order to determine the feasible role of monooxygenases in regulation of the macrophage acyl-CoA: cholesterol acyltransferase (ACAT) activity, the effects of ketoconazole on the activities of benz(a)pyrene hydroxylase and ACAT as well as on the [14C]oleate incorporation into cholesterol esters in cultured mouse peritoneal macrophages (MPM) were studied. Ketoconazole (0.5-50 M) inhibited the benz(a)pyrene hydroxylase activity but increased the free cholesterol (FC) level in MPM cultured with an acetylated low density lipoprotein (acetyl-LDL). An addition of ketoconazole (1-50 M) eliminated the increase in the rate of FC esterification after incubation of MPM with acetyl-LDL (but not with 25-hydroxycholesterol). In contrast, progesterone, an ACAT activity inhibitor, used at 5-30 M diminished the rate of FC esterification, when MPM were incubated with acetyl-LDL of 25-hydroxycholesterol. Ketoconazole provoked a dose-dependent decrease of the [3H]FC incorporation into macrophage polar oxysteroids. The data obtained suggest that the ketoconazole (1-30 M) effect on FC esterification in MPM cultured with acetyl-LDL is determined by its inhibiting monooxygenases, which produce oxidized forms of FC that are potential activators of ACAT.