In vitro and in vivo evaluation of effects of a heptanoyl tripeptide, FK-565, on porcine macrophage and lymphocyte function

A series of experiments was performed in vitro and in vivo to determine the influence of FK-565, a heptanoyl tripeptide, on lymphocyte and macrophage function in swine. Compared with values for control cultures, mitogen-stimulated lymphocyte blastogenesis and interleukin-2 production were unaffected in cells preincubated with 0.1, 1.0, and 10.0 micrograms of FK-565/ml. Natural killer cell activity was increased by preincubation with 1.0 microgram of FK-565/ml; however, this increase was not statistically significant. In vitro treatment of porcine alveolar macrophages with FK-565 did not enhance cytolytic activity or bactericidal activity. In in vivo experiments, FK-565 given orally to pigs at concentrations of 6 or 60 micrograms.kg-1.d-1 for 5 days did not affect lymphocyte blastogenesis, interleukin-2 production, or alveolar macrophage bactericidal activity. A trend toward increased natural killer cell activity was evident in pigs treated with FK-565. In contrast, pigs treated with 6 micrograms.kg-1.d-1 had significantly (P less than 0.01) decreased alveolar macrophage cytolytic activity. These data indicate that at the dosages tested, FK-565 is not a suitable immunomodulator for enhancement of nonspecific immunity in swine.     

Evaluation of a biological response modifier: effects on starter pig performance

The influence of a biological response modifier (FK-565) on weanling pig performance was evaluated. One hundred twenty-five weanling pigs (weaned at 21 +/- 3 d) averaging 6.3 kg were utilized in a 35-d growth trial. Dietary treatments included a basal diet (1.25% lysine, corn-soybean meal-dried whey), the basal plus .1, 1 or 10 ppm FK-565 and the control plus an antibacterial combination containing chlortetracycline, sulfamethazine and penicillin. Performance was recorded weekly, and on d 35 all pigs were bled for whole blood and serum chemistry profiles and then were euthanatized. Heart, liver, kidneys and spleen weights were recorded. Also, gross and histological examinations were made of these organs, as well as sections of lung, ileum, bone marrow, thymus and mesenteric lymph node. By d 14, pigs fed the antibacterial diet gained faster (P less than .06) than pigs fed the control and FK-565 diets. However, no differences (P less than .10) in feed intake at d 14 or efficiency of feed utilization at either d 14 or 35 were observed. For the overall 35-d trial, ADG was greater (P less than .01) for pigs consuming the antibacterial diet than for pigs consuming control and the FK-565 diets. Pigs consumed more of the antibacterial diet than of the other diets (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative and qualitative properties of host polymorphonuclear cells during experimentally induced Staphylococcus aureus mastitis in cows

Polymorphonuclear cells have a critical role in the pathogenesis of bovine mastitis. We have documented that experimentally induced Staphylococcus aureus mastitis is associated with cyclic increase and decrease in the quantity of viable bacteria shed in the milk. Concomitant with this cycling of bacteria is an inverse cycling of the hosts cells within the milk. Such somatic cells were determined to be greater than or equal to 95% polymorphonuclear cells. The quality of these cells was evaluated by measuring their relative efficiency of bacterial killing and phagocytosis at various times during an infection. Host polymorphonuclear cells had as much as 10,000-fold variation in the bactericidal failure rate for staphylococci during cell cycling. The most efficient bactericidal effect was observed at or near the peak of the somatic cell count (SCC). The ability of these cycling cells to ingest fluorescent beads was also quantitated by use of flow cytometry. The percentage of phagocytic polymorphonuclear cells that ingested fluorescent latex beads ranged from 15 to 80% of the total cell population during cell cycling, and tended to be optimal at or near peak SCC. In addition, the average number of beads ingested varied between 1 and 2 particles/polymorphonuclear cell, with as many as 17% of the phagocytic cells ingesting 4 or more beads at maximal efficiency. Polymorphonuclear cells from quarters infected with S aureus varied quantitatively (total SCC) and qualitatively (bactericidal activity and phagocytic ability) during the course of an infection. Not only is the quantity of host's phagocytic cells in the mammary gland central to the defense mechanism against infection, but the biological activation state appears to be equally important. The role of these cells in the pathogenesis of a cycling infection is presented in a model to explain the cyclic nature of mastitis.     

Immune response in mice infected by Encephalitozoon cuniculi and suppressed by dexamethasone

Several indicators of immune response were observed in immunocompetent mice of the ICR line and those suppressed by dexamethasone upon their experimental infection with the microsporidia of Encephalitozoon cuniculi. The mice were infected by one-shot intraperitoneal administration of 5 x 10(7) pathogenic spores. On Days 7, 14, 28 and 42 after infection, peripheral blood leukocyte phagocytic activity was determined and compared, including phagocytic index and the blastogenic response in spleen cells to mitogenic activation by concanavalin A and phytohaemagglutinin. The results point to the fact that E. cuniculi itself can cause a significant decrease in phagocytic activity of phagocytic leukocytes in the early stages of infection as well as a remarkable decrease in the proliferative response of spleen cells to T-cellular mitogens.     

The effect of parainfluenza virus type 3 and Pasteurella haemolytica on oxygen-dependent and oxygen-independent bactericidal mechanisms of ovine pulmonary phagocytic cells

Groups of caesarean-derived, colostrum-deprived lambs were inoculated by the intratracheal route with Pasteurella haemolytica, either alone or 4 or 6 days after the inoculation of parainfluenza virus type 3 (PI3). Other groups were inoculated with PI3 followed by veal infusion broth, or with uninfected cell culture fluid followed by veal infusion broth (controls). All lambs were killed 24 h after the second inoculation. Pulmonary phagocytic cells were recovered by lavage and separated into alveolar macrophage (AM) and neutrophil fractions by density gradient centrifugation. Bacterial proliferation was detected in the lungs of all five lambs inoculated with P. haemolytica 6 days after PI3 but in only one of five inoculated with P. haemolytica 4 days after PI3 and one of five inoculated with P. haemolytica alone. The number of phagocytic cells recovered from the lungs was highest in animals inoculated with P. haemolytica 6 days after PI3 and, overall, a greater number of both AM and neutrophils was recovered from the lungs of animals where bacterial proliferation occurred (greater than 10(5.0) P. haemolytica 100 g-1 lung) than from those that controlled the bacterial infection. Oxygen-dependent bactericidal activity of AM and neutrophils was measured by chemiluminescence. Infection with PI3 and P. haemolytica increased the chemiluminescence responses. The highest responses were recorded from lambs inoculated with P. haemolytica 6 days after PI3, the group where pulmonary clearance was poorest. Overall, responses were higher in lambs in which bacterial proliferation occurred than in those that controlled the infection. On the other hand, oxygen-independent bactericidal activity, measured by the direct effects of neutrophil lysates on Escherichia coli, was lowest in lambs inoculated with P. haemolytica 6 days after PI3 and was lower in lambs where bacterial proliferation occurred.     

Modulation of juvenile brook trout (Salvelinus fontinalis) cellular immune system after Aeromonas salmonicida challenge

In fish, the first line of defence against infectious microorganisms is based on non-specific cellular immune mechanisms (innate immunity). In this study, we measured the non-specific immune parameters (natural cytotoxic cells (NCC) activity, lymphoproliferation, percentage of phagocytosis and phagocytic activity) in brook trout (Salvelinus fontinalis) infected by a virulent strain of Aeromonas salmonicida. Eight days post-infection, the mortality of infected fish reached 70%. A transient immunostimulation of the NCC activity was noticed 24h post-infection, but there was no significant difference at 48 h. Then, infection of brook trout with A. salmonicida induced a biphasic immune response. At 24h post-infection, lymphoproliferation was drastically depressed but returned to control level at 96 h. A slight increase in the percentage of phagocytosis and the phagocytic activity was noticed throughout the experiment. Conversely the cell mortality was significantly higher in infected fish compared to control. The modulation of immunological parameters might reveal important clues on how innate immunity might protect fish from bacterial infections.     

Phagocytosis in calves and its dynamics after experimental treatment

We evaluated the phagocytic capacity of blood neutrophils and monocytes in calves after nonspecific stimulations of the organisms by colloidal charcoal and concentrated blood derivative administered alone, or enriched by immunomodulator (levamizol). Each of the above-mentioned preparations could be characterized by a specific response of the organism with respect to the phagocytic capacity. After administration of colloidal charcoal, both the phagocytic activity (percent of phagocytizing cells) and the particle-ingesting ability, i.e. phagocytic index, which showed two-phase changes in relation to the administration, were simulated. An increase in the phagocytic index was retained until the end of observation (four weeks), but the phagocytic activity (percent of phagocytizing cells) dropped to the level before administration as soon as in 24 hours. The phagocytic activity was also positively stimulated by the concentrated blood derivative administered alone, and the particle-ingesting ability was not influenced very much. The concentrated blood derivative with immunomodulator could be characterized by a fast increase in the phagocytic activity, accompanied by a successive short-time rise of the phagocytic index. A joint feature of all three preparations was a simultaneous increase in the percent of potential phagocytes and in the values of phagocytic activity. In none of the cases was, however, the increase in phagocytic activity accompanied by a rise in the phagocytic index.     

Functions of neutrophils in sheep experimentally infected with Ehrlichia phagocytophila

Ehrlichia phagocytophila infection in sheep is characterized by persistent neutropaenia, indicative of decreased phagocytic capacity. This predisposes infected animals to other infections. A whole blood flow cytometrical method was used to document the degree and extent of reduced phagocytic and respiratory burst activity in phagocytes during an experimental infection with E. phagocytophila, and monitored until 56 days post-infection. Six sheep at 5 months of age were inoculated with an intravenous injection of infected blood. Six age-matched sheep were used as controls. A period of reduced respiratory burst lasting up to Day 17 post-infection was recorded. The population of cells showing phagocytic activity without respiratory burst was larger in the infected animals compared to controls up to Day 45 post-infection.     

Experimental Burkholderia pseudomallei infection of pigs

Experimental infection with Burkholderia pseudomallei was successfully produced after a single intravenous challenge of 2-month-old pigs with a dose of 5.0 x 10(9) bacterial cells. Clinical, paraclinical and morphological findings of the infectious process and post-infectious immunity were examined up to day 30 post infection (p.i.). A transient and short hyperthermia accompanied by enhanced and longer demonstrated pulse frequency. An increased erythrocyte sedimentation rate and tachypnea were observed too after clinical examination. The infection starts with significant leucopenia, and a reduced number of alveolar and peritoneal macrophages which have been overcome in the latest intervals of infection. In contrast, the phagocytic activity of leucocytes was statistically increased during the course of infection and up to day 15 p.i. in the case of alveolar macrophages. Burkholderia pseudomallei was able to colonize the lungs during the whole experiment and was only present 3 days in the spleen and mesenterial lymph nodes (MLN). Significant antibody response was developed as early as day 7 p.i. Hyperaemia, haemorrhages and necrotic foci were found in the brain, liver spleen and MLN. Lung tissue was also hyperaemic, with formation of small abscesses and signs of catarrhal pneumonia. Data obtained in this study revealed that B. pseudomallei causes a chronic generalized infection in pigs, even after intravenous challenge.     

Enhancement of phagocytic and chemokinetic activities of rainbow trout head kidney cells by C-reactive protein

OBJECTIVE: To investigate immunostimulating activity of purified rainbow trout (Oncorhynchus mykiss) C-reactive protein (CRP) on trout phagocytic cells. ANIMALS: 20 rainbow trout and 2 rabbits. PROCEDURE: The effect of CRP on phagocytic activity of head kidney (HK) cells was examined by use of a phagocytosis assay with plastic particles. The enhancing effect of CRP on migration activity of HK cells was examined by use of the blind well assay. RESULTS: Glass-adherent cells from clinically normal trout had increased dose-dependent phagocytic activity against plastic particles when cells were incubated in the presence of CRP. Pretreatment of particles with CRP also enhanced phagocytic activity of the cells, indicating an opsonic effect of CRP. Rabbit anti-trout CRP serum suppressed the enhancing activity of CRP. The HK cells had significant dose-dependent chemokinetic activity against CRP that was not inhibited by anti-CRP serum, indicating that a CRP-antibody complex also could be chemokinetic. CONCLUSIONS: Rainbow trout CRP has immunostimulating activity for HK cells, resulting in enhanced phagocytic and chemokinetic activities.     

The role of phagocytic cells in enhanced susceptibility of broilers to colibacillosis after Infectious Bronchitis Virus infection

Colibacillosis results from infection with avian pathogenic Escherichia coli bacteria. Healthy broilers are resistant to inhaled E. coli, but previous infection with vaccine or virulent strains of Infectious Bronchitis Virus (IBV) predisposes birds for severe colibacillosis. We investigated whether IBV affects recruitment and function of phagocytic cells and examined NO production, phagocytic and bactericidal activity, and kinetics of peripheral blood mononuclear cells (PBMC) and splenocytes. Moreover, we measured cytokine mRNA expression in lung and spleen samples. Broilers were inoculated with IBV H120 vaccine or virulent M41 and challenged 5 days later with E. coli 506. A PBS control and E. coli group without previous virus inoculation were also included. Birds were sacrificed at various time points after inoculation (h/dpi). Inoculation with IBV induced extended and more severe colibacillosis than with E. coli alone. At 4dpi, the number of KUL-01(+) PBMC in all E. coli-inoculated groups was significantly higher than in PBS-inoculated birds, which correlated with lesion scores. From 1 to 4dpi, NO production by PBMC from all E. coli-inoculated animals was elevated compared to PBS birds. Bactericidal activity of PBMC in IBV-inoculated animals at 7dpi was lower than in PBS- and E. coli-inoculated birds, but phagocytic capacity and recruitment were not severely impaired. In spleen samples of IBV-infected animals reduced expression of IL-1beta, IL-6, IL-8, IL-10, IL-18 and IFN-gamma mRNA was found 1dpi. Our results suggest that enhanced colibacillosis after IBV infection or vaccination is caused at least by altered innate immunity and less by impairment of phagocytic cell function.     

Bacterial lipopolysaccharide stimulates bovine neutrophil production of TNF-alpha, IL-1beta, IL-12 and IFN-gamma

After intramammary infection, polymorphonuclear neutrophil leukocytes (PMN) are the first cells recruited into the mammary gland. Rapid recruitment of and bacterial phagocytosis and killing by PMN are the most effective defenses against establishment of bacterial infection. In addition to their phagocytic and bactericidal properties, PMN may play a key supportive role through secretion of cytokines during the innate immune response. We sought to determine whether bovine PMN produce cytokines in response to stimulation by lipopolysaccharide (LPS). To investigate the effects of LPS on the expression of cytokines secreted by bovine PMN, we measured the expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-12, and interferon (IFN)-gamma by ELISA after stimulation with different concentrations of LPS, and secretion of IL-8 after co-stimulation with LPS and either TNF-alpha or IL-1beta. Bovine PMN were shown to secrete TNF-alpha , IL-1beta, IL-12, IL-8 and IFN-gamma in response to LPS. Co-incubation of PMN with LPS and TNF-alpha increased secretion of IL-8 when compared to LPS alone. It was concluded that LPS stimulation up-regulates the secretion of cytokines by bovine PMN, and that co-incubation of LPS with TNF-alpha had an additive effect on the secretion of IL-8. These data show that bovine PMN, in addition to their phagocytic and bactericidal properties, may play a supportive role in the innate immune response to infection by Gram-negative bacteria through their ability to produce immuno-regulating cytokines.     

The exacerbating effect of infectious bronchitis virus infection on the infectious bursal disease virus-induced suppression of opsonization by Escherichia coil antibody in chickens

Chickens infected with infectious bronchitis virus (IBV) and infectious bursal disease virus (IBDV) commonly develop secondary infection of the respiratory tract with Escherichia coli, resulting in significant economic losses. To understand the host factors that may contribute to the E. coli infection, we investigated macrophage-mediated E. coli phagocytosis, intracellular bacterial killing, and development of opsonizing antibody in previously uninfected chickens and in those infected with IBV, IBDV, and IBDV plus IBV. Macrophages from the peripheral blood and the respiratory tracts of chickens infected with IBV or IBDV plus IBV efficiently performed in vitro phagocytosis of E. coli in the presence of positive-control serum (i.e., E. coli antiserum produced in normal chickens). Those macrophages also had adequate bactericidal activity, indicating that IBV and IBDV infections had not affected their phagocytic activity or bactericidal function. The phagocytic activity of macrophages remained unaffected (P < 0.05) when the positive-control serum was replaced with E. coli antiserum produced in chickens infected with IBV alone. However, when E. coli antisera raised in IBDV-infected and, especially, that produced in IBDV plus IBV-infected chickens were supplemented, the percentage of phagocytosis and number of bacteria ingested per phagocyte were significantly (P < 0.05) less. These results indicate that although IBDV alone has the potential to markedly reduce opsonizing ability of antibody, this effect is significantly (P < 0.05) exacerbated by IBV infection.     

Immunotherapeutic potential of Ocimum sanctum (L) in bovine subclinical mastitis

Immunotherapeutic potential of aqueous extract of Ocimum sanctum (O. sanctum) leaf in bovine sub-clinical mastitis (SCM) was investigated. Somatic cell count (SCC), total bacterial count (TBC), milk differential leukocyte count (DLC), phagocytic activity and Phagocytic index and leukocyte lysosomal enzymes like myeloperoxidase and acid phosphatase content were evaluated after intramammary infusion of aqueous leaf extract of O. sanctum. The results revealed that the aqueous extract of O. sanctum treatment reduced the TBC and increased neutrophil and lymphocyte counts with enhanced phagocytic activity and phagocytic index. Similarly, the lysosomal enzymes contents of the milk polymorphonuclear cells (PMNs) were also enhanced significantly in animals treated with the extract. The results suggest that the crude aqueous extract of O. sanctum (leaf) possesses some biologically active principles that are antibacterial and immunomodulatory in nature. As such, the present wok substantiates the therapeutic use of medicinal herb and also emphasizes on the potential of the commonly available non-toxic substances to enhance the mammary immunity.     

The effect of Pasteurella haemolytica A2 infection on phagocytosis efficiency of caprine broncho-alveolar macrophages

An experiment was designed to study the in vivo effect of Pasteurella haemolytica A2 infection on the phagocytosis activity of caprine broncho-alveolar macrophages and the extent of pneumonic lesions. Twelve healthy local Kacang goats, about 7 months of age, were divided into two groups of six. Goats in group 1 were inoculated intratracheally with 4 ml inoculum containing 2.8 x 10(9) colony-forming units (CFU)/ml of Staphylococcus aureus. Goats in group 2 were inoculated intratracheally with 4 ml of inoculum containing 9.5 x 10(8) CFU/ml of Pasteurella haemolytica A2 isolated earlier from pneumonic lungs of goat. At intervals of 3 and 7 days post-challenge five goats from each group were killed and the lungs were washed with sterile phosphate-buffered saline. Smears were prepared from the lung washing fluid and the number of macrophages with phagocytic activity was determined. At day 3 post-infection, goats of both groups showed a similar pattern of pneumonic lesion. The lung washing fluid of goats in group 2 was found to contain numerous neutrophils and macrophages. Goats in group 2 showed significantly (P < 0.05) higher extent of lung lesions than group 1. Similarly, the average extent of lung lesions was significantly (P < 0.05) more severe in group 2 at day 7 post-infection. The lung washing fluid contained mostly macrophages. The phagocytic activity following S. aureus infection was more efficient and significantly (P < 0.01) higher compared with infection by P. haemolytica A2. There were weak correlations between the extent of pneumonic lesion and the phagocytic activity. Thus, goats with poor phagocytic activity were likely to develop more extensive lung lesions.     

Phagocytosis and destruction of Staphylococcus aureus

Summary

A review is presented of the phagocytosis and intracellular killing of Staphylococcus aureus by polymorphonuclear and mononuclear leukocytes. Recruitment of adequate numbers of leukocytes to the site of infection occurs through the process of chemotaxis. Recognition of invading staphylococci by the phagocytic cells is mediated through bacterial opsonization. Both processess depend upon the activation of the heat‐labile complement system which generates the majority of chemotactic (C5a) and opsonic (C3b) molecules for S. aureus phagocytosis. The key role of peptidoglycan in the cell wall of staphylococci in these events is stressed. Attachment and ingestion of opsonized staphylococci occurs via poorly‐defined receptors for opsonins in the membrane of the leukocyte. The greater phagocytic capacity of neutrophils as compared to monocytes is not reflected in differences in their membrane receptors for staphylococcal opsonins. Once ingested, staphylococci are rapidly destroyed by oxygen‐dependent and oxygen‐independent bactericidal mechanisms of the phagocytes. Small numbers of S. aureus may survive within the leukocyte. Special attention is focused on the numerous ways S. aureus is able to hinder, evade, and directly damage the phagocytic defense mechanisms of the host.     

Immunological and gene expression responses to a Salmonella infection in the chicken intestine

Besides infection in humans, Salmonella enteritidis can also cause serious illness in young chickens. However, the genetic and immunological parameters important for the disease in chickens are not well characterized. In this study, processes in the chicken intestine in response to a Salmonella infection were investigated in two different chicken lines. One-day-old chickens were orally infected with Salmonella. T-cell subpopulations, phagocytic properties of intestinal mononuclear cells and RNA expression levels of the jejunum were investigated. The two chicken lines differed in the amount of cfu in the liver and growth retardation after the infection. Differences in phagocytic activity of intestinal mononuclear cells were found between control and Salmonella infected chickens. The number of CD4+ T-cells of the intestine decreased after the Salmonella infection in one chicken line, while the number of CD8+ T-cells increased in both chicken lines, but the time post infection of this increase differed between the lines. In one chicken line the expression levels of the genes carboxypeptidase M and similar to ORF2 decreased after the Salmonella infection, which might be related to a decrease in the amount of macrophages. With the microarray, ten genes were found that were regulated in only one of the chicken lines, while we found six genes regulated in response to the infection in both chicken lines. So differences in genetic background of the chickens influence the intestinal host response of the Salmonella infection as observed by phagocytic activity, gene expression and changes in the number of T-cell subpopulations and macrophages.     

Comparisons of nonspecific and specific immunomodulation by oxolinic acid, oxytetracycline and levamisole in salmonids

Oxolinic acid, a promising drug for the treatment of bacterial fish disease agents, was tested for possible immunomodulatory effects on fish. Another antibiotic oxytetracycline, known to be immunosuppressive at higher treatment doses, and levamisole, a known immunostimulator for higher vertebrates, were also compared for causing changes in the nonspecific defense compartment and the specific immune system in rainbow trout. Groups of fish were immunized with Yersinia ruckeri O-antigen bacterin in combination with selected doses of the drugs. The nonspecific defense activity was measured by demonstrating neutrophil metabolic activity by the nitroblue tetrazolium assay, by counting engulfed bacterial cells for a phagocytic index and by counting leukocytes with adherent bacterial cells for the adherence index. The specific immune response was monitored by the passive hemolytic plaque assay demonstrating the numbers of antibody-producing cells. The results showed that oxolinic acid, used at recommended doses for the treatment of bacterial diseases, did not cause immunosuppression in either the nonspecific defense or specific immune system compartments, whereas tetracycline at 10 mg/kg caused reduced activity in both. Fish given levamisole injections before the antigen injection showed a stimulated nonspecific defense but a much reduced specific immune response.     

The role of first line of defence mechanisms in the pathogenesis of cellulitis in broiler chickens: skin structural, physiological and cellular response factors

The present study examined several basic attributes of first-line defence mechanisms in the skin as potential factors that may explain the susceptibility of broiler chickens to cellulitis. The variables including structural characteristics of the skin, physicochemical properties and cellular responses to the challenge with pathogens were compared between two categories of chickens, a strain of fast-growing commercial broiler chickens (susceptible to cellulitis) and leghorn chickens (resistant to cellulitis). There were substantial differences between leghorns and broilers with regard to physiological characteristics of the skin. Broiler skin was more amenable to injury and the wound-healing process was slow. Compared with leghorns, the lesions resulting from sub-dermal challenge in broilers were more severe and disseminated over a larger area. Mobilization of phagocytic cells (heterophils and macrophages) in leghorns was brisk even in the areas distant from the site of infection, whereas only few heterophils were recruited in the skin of broilers. The functional competence of heterophils in broilers was inferior when compared with leghorns. Based on the present finding, the predisposition of broilers to cellulitis appears to be primarily associated with the inferior first line of defence of their skin. Broilers in commercial situations may be at higher risk to succumb to even minor infection and eventually develop cellulitis because: (1) structural weaknesses of the skin may predispose broilers to skin injury and thus the risk of skin infection by pathogens is increased; (2) broiler skin surface is more likely to provide a conducive environment for colonization of Escherichia coli; (3) in the event of infection, poor recruitment of phagocytic cells to the site of infection may readily lead to widespread colonization of the tissue by pathogens causing cellulitis and (4) poor functional quality of the phagocytic cells that are mobilized compromise the ability of the host to contain the spread of infection.     

Electron microscopic study of the peritoneal macrophages of rats with chronic fascioliasis and the carcinogenic effect of diethylnitrosamine

The ultrastructure of peritoneal macrophages of rats with chronic fascioliasis and the carcinogenic effect of diethylnitrosamine (DENA) were studied. The phagocytic activity of macrophages on Staphylococcus aureus were examined in its dynamics (in the 1st, 5th and 24th h). The ultrastructural changes of the macrophages were the most pronounced in animals injected eight times with DENA and the weakest in the group of animals infected twice with Fasciola hepatica. As to the phagocytic activity of the macrophages the following events were observed: attraction and adhesion of the bacterial cells to the surface of the macrophages, their inclusion in phagosomes; partial to full lysis of the bacteria; and formation of residual bodies. The phagocytosis was the most active in macrophages obtained from animals infected twice with Fasciola hepatica and the weakest in those from the DENA-treated animals.