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PubMed2001

Does [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] dichloroplatinum(II) act as an immune response modifier? IV. Inhibition of the proliferation-increasing effect of progressively growing MXT-M-3,2 breast cancer on phagocytes by the title compound.

In female B6D2F1 mice bearing an MXT-M-3,2 breast cancer graft the level of the phagocytic cells (e.g. of granulocytes and macrophages in the spleen and of granulocytes and monocytes in the blood) is significantly elevated. The positive correlation between the number of the phagocytic cells and the weight of the tumor indicates that the MXT-M-3,2 breast cancer promotes myelopoiesis, presumably by secretion of hematopoietic growth factors like GM-CSF. This process can be described for each phagocyte type by a regression equation. Due to its hormonal potency [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] dichloroplatinum(II) (meso-1-PtCl2) can reduce the excessive numbers of the granulocytes and macrophages, which seem to be responsible for the progressive growth of the MXT-M-3,2 breast cancer. This process leads to an interruption of the vicious circle of mutual growth stimulation of breast cancer cells and these phagocytes. The target of meso-1-PtCl2 is the estrogen receptor (ER) of the breast cancer cell. The interaction between meso-1-PtCl2 and the ER presumably results in a diminished secretion of hematopoietic growth factors and hence in a decline of the number of phagocytic cells. Meso-1-PtCl2 does not inhibit the proliferation of tumor cells by direct interaction with their DNA, as is described for platinum complexes like cDDP. In its mode of action the equipotent, breast cancer inhibiting drug cDDP differs from meso-1-PtCl2. This is obvious from the fact that in cDDP--but not in meso-1-PtCl2-treated, tumor bearing mice the number of granulocytes and macrophages does not markedly deviate from that in untreated control mice with tumors of the same weight. The drug cDDP probably does not interfere with the mechanism of the secretion of hematopoietic growth factors. The reduction of the number of tumor cells by cDDP leads to a decline of the number of phagocytic cells in accordance with the respective regression equations. In contrast to meso-1-PtCl2 and cDDP, ovariectomy causes elevated phagocyte numbers, probably due to the strongly reduced estrogen level. The studies described in this publication indicate that the anti-breast cancer activity of meso-1-PtCl2 is caused by a decimation of phagocytes and with this by an abolition of the tumor promoting effect. Furthermore, a restoration of the natural immunosurveillance seems to be of importance.

Adjuvants, Immunologic↗

PubMed1982

Characterization of mononuclear phagocytes from the mouse, guinea pig, rat, and man.

The present paper describes cytochemical, membrane, functional, and mitotic characteristics of monoblasts, promonocytes, monocytes, and macrophages of the mouse, guinea pig, rat, and man. For all of these species the results show that after staining for nonspecific esterase, with alpha-naphthylbutyrate as substrate, and for lysozyme, mononuclear phagocytes can be distinguished from other cells, e.g., T and B lymphocytes. However, it must be kept in mind that immature and mature granulocytic cells are also lysozyme positive. The presence of Fc and C receptors is dependent on the maturity of the cells and the duration of incubation in vitro; with respect to the former, an in vivo population of immature mononuclear phagocytes may have a lower percentage of positive cells than is the case in a mature population, and with respect to the latter, the percentage of positive cells rises during incubation. Phagocytosis of opsonized bacteria and red cells is a reliable criterion for the distinction between mononuclear phagocytes and other cell types, e.g. lymphocytes and fibroblasts. In all of the species studied, the majority of both immature and mature mononuclear phagocytes ingested particles opsonized with IgG; the proportion of phagocytosis of red cells via C3 receptors is usually very small. Incorporation studies with [3H] thymidine have shown that immature mononuclear phagocytes (i.e., monoblasts and promonocytes) divided and that monocytes and macrophages do not. The small number of macrophages that incorporate [3H] thymidine are immature mononuclear phagocytes which have very recently arrived in the tissues from the bone marrow. Comparison of mononuclear phagocytes in different organs of various species has shown unequivocally that these cells belong to one cell line, called the mononuclear phagocyte system.

Animals↗

PubMed1988

The three different phases of reticuloendothelial system phagocytic function in rats with liver injury.

In the present study, reticuloendothelial system (RES) phagocytic function of rats with partial hepatectomy or experimentally induced liver cirrhosis was investigated by determining the phagocytic index, the opsonic index, and uptake rate in liver, spleen, and lung of a 51Cr-labeled endotoxin-injected rat. In both the partially hepatectomized and the cirrhotic rats, all three indicators varied markedly according to the elapsed period since liver injury. The changes in RES phagocytic function were classified into three different phases: compromised, compensatory, and enhanced. The compromised phase, consisting of a decrease in the phagocytic index, was observed during the first 24 hr after 67% hepatectomy and in advanced liver cirrhosis. This represented the failure of RES phagocytic function. The compensatory phase, in which the phagocytic index was maintained at nearly normal levels mainly by a compensatory enhancement in the opsonic index, was seen during the first to second postoperative day and in moderate liver cirrhosis. The enhanced phase, with a high phagocytic index, was observed from Day 4 to approximately Day 14 after surgery, and in the cases of mild liver damage. In the compromised and compensatory phases, the liver uptake rate was significantly decreased compared with the control. However, the uptake in the spleen and lung were markedly increased. In conclusion, the phagocytic function of the RES was significantly affected to a degree which changed with the extent of liver damage.

Animals↗

PubMed1982

Augmentation of the phagocytic activity of murine spleen cell populations induced by Adriamycin.

C57B1/6 mice were injected i.v. with Adriamycin (5 mg/kg) and various days later, spleen cells were tested for Fc dependent phagocytic activity by measuring protection of 51Cr-labelled, antibody coated SRBC from hyptonic shock. No difference in phagocytic activity was observed with spleen cells from untreated mice or mice treated with Adriamycin 1-7 days prior to killing. Increases in phagocytic activity were, however, seen with spleen cells from mice treated 9 to 13 days prior to killing. Phagocytic activity of spleen cells from mice treated 5 days prior to killing was increased after these cells were cultured for 5 days when compared to cultured cells from untreated mice. Despite depletion of mature phagocytic cells from spleen cells suspensions by silica treatment, followed 24 hours later by silica removal by density gradient centrifugation, phagocytic activity was observed with spleen cells from ADM treated mice (day-5) after 5 days in culture. No phagocytic activity was seen with spleen cells from untreated mice using the same silica treatment and culture conditions. When cultured spleen cells from untreated or ADM treated mice (day-5) were fractionated by plastic adherence, twice as many adherent cells were removed compared to controls. Their phagocytic activity (per cell) was, however, the same. Thus, ADM may increase the number of immature nonphagocytic macrophages in the spleen resulting in increased mature macrophages after culture.

Adjuvants, Immunologic↗

PubMed2006

Respiratory burst activity of Atlantic cod (Gadus morhua L.) blood phagocytes differs markedly from that of rainbow trout.

In the present study we investigated the respiratory burst (RB) activity of Atlantic cod (Gadus morhua L.) blood phagocytes and we evaluated how the RB activity of cod blood cells differ from that of trout. The RB activities were measured directly from highly diluted whole blood as luminol-amplified chemiluminescence (CL) under various conditions. Studies regarding the blood dilutions for cod whole blood chemiluminescence measurements (WBCL) revealed that at a final blood dilution of 1.5 microl ml(-1) or less the CL response was strictly proportional to the number of phagocytes. This range of blood dilution did not markedly differ from that of trout. However, the opsonisation capacity of cod plasma was markedly poorer. The RB activity of phagocytes was most active at 15 degrees C when heterologous cod serum was used as a source of opsonin, whereas at final blood dilution of 8.0 microl ml(-1) (when homologous cod plasma was at a higher concentration) the highest RB activity was observed at 10 degrees C. Aeromonas salmonicida strain MT004 (As MT004) induced higher RB activity than the two known pathogens for cod, atypical A. salmonicida and Vibrio anguillarum. Cod blood phagocytes were more responsive to plastic surfaces and the adhesion response of phagocytes was partly inhibited but did not totally vanish even at a final gelatin concentration of 0.4%. Moreover, cod serum enhanced the adherence of phagocytes and cod blood phagocytes also showed slow spontaneous degranulation. Finally, within the tested anticoagulants (heparin, Na-citrate, EDTA) heparin treated blood phagocytes generated the highest RB activity.

Aeromonas salmonicida↗

PubMed2003

Naphthalene-induced differential tissue damage association with circulating fish phagocyte induction.

The effect of naphthalene on phagocytes and associated abnormal cellular activities was studied in Anguilla anguilla L. Fish were exposed to sublethal concentrations (0.1, 0.3, 0.9, 2.7 microM) of naphthalene for 8, 16, 24, 48, and 72 h. Gill, head kidney, and peritoneum phagocyte respiratory burst activity (RBA) was measured by nitroblue tetrazolium reduction assay, whereas lipid peroxidation in fish gill, kidney, and liver was measured by thiobarbituric acid reaction substance. A significant increase (P < 0.05-P < 0.001) in total cell count (TCC) of phagocytes (TCCPH) isolated from gill, head kidney, and peritoneum was observed after 8 h of naphthalene exposure and persisting at 16 h exposure. However, long-term exposures (24, 48, and 72 h) induced a significant (P < 0.05-P < 0.001) decrease in TCC at all the concentration levels. Naphthalene exposure caused a significant (P < 0.05-P < 0.001) RBA induction after 8 and 16 h in gill, head kidney, and peritoneal phagocytes, which consequently resulted in a significant (P < 0.01 and P < 0.001) peroxidative tissue damage increase measured as lipid peroxidation (LPO) in gill, kidney, and liver at the same time intervals. Considering TCCPH, RBA, and LPO, the most affected tissues were gill and kidney after 8 and 16 h exposure to all naphthalene concentrations. RBA was significantly decreased after 24, 48, and 72 h of exposure (P < 0.05-P < 0.001), whereas peroxidative damage increased significantly (P < 0.05-P < 0.001) and persisted in long-term exposures (72 h) at all concentration levels in gill and kidney. Liver short-term exposure (8 and 16 h) to all naphthalene concentrations did not alter LPO activity. Long-term exposures (48 and 72 h) caused a significant (P < 0.01 and P < 0.001) LPO increase, which was more pronounced at 72 h. The results demonstrate that the activation pattern of RBA was corroborated by the extent of phagocyte-induced peroxidative damage in the tissues, as demonstrated by a significant increase of circulating phagocytes. However, the route of exposure and mode of entry of a pollutant may affect the activation pattern of circulating fish phagocytes. It is proposed that measurement of phagocyte-induced reactive oxygen species and their association with peroxidative damage in fish tissues may prove to be useful in biomonitoring fish exposure to aquatic pollutants.

Anguilla↗

PubMed2000

Supernatants from leucocytes treated with melanin-concentrating hormone (MCH) and alpha-melanocyte stimulating hormone (alpha-MSH) have a stimulatory effect on rainbow trout (Oncorhynchus mykiss) phagocytes in vitro.

Melanin-concentrating hormone (MCH) and alpha-melanocyte stimulating hormone (alpha-MSH) are widespread vertebrate neuropeptides. In teleost fish the peptides are involved in the hormonal control of skin pigmentation, but they have also been shown to modulate corticosteroid secretion in both fish and mammals. alpha-MSH has additional potent anti-inflammatory actions in mammals and both peptides stimulate leucocyte phagocytosis in rainbow trout in vitro. The effects of these peptides on phagocytosis and the release of immunomodulatory factors by rainbow trout head kidney leucocytes were investigated in vitro. Neither MCH nor alpha-MSH had any effect on the adherence of phagocytes to glass slides or the activity of isolated phagocytes. When added to mixed leucocyte suspensions, however, MCH (50 and 100nM) and alpha-MSH (1 and 10nM) significantly increased the percentage of cells undergoing phagocytosis and MCH (50nM), but not alpha-MSH, stimulated the phagocytic index. In subsequent experiments, isolated phagocytes were exposed to supernatants derived from mixed leucocyte suspensions exposed to MCH (50 and 100nM) and alpha-MSH (1 and 10nM). Supernatants from leucocytes exposed to all doses of the peptides significantly increased the percentage phagocytosis and those from cells stimulated with MCH (100nM) and alpha-MSH (1 and 10nM) increased the phagocytic index of the phagocytes. The results suggest that cells other than phagocytes are required for MCH and alpha-MSH to exert their stimulatory effects on trout phagocytic cells through the release of one or more macrophage-activating factors.

Animals↗

PubMed1996

Phagocytic function and metabolite production in thioacetamide-induced liver cirrhosis: a comparative study in perfused livers and cultured Kupffer cells.

BACKGROUND/AIMS: The aim of the study presented here was to evaluate the basal and stimulated phagocytic activities and the metabolite production of isolated perfused livers, and also the phagocytic capacity of cultured Kupffer cells from rats with macronodular cirrhosis. METHODS: Rats were made cirrhotic by oral administration of thioacetamide. The phagocytic activity was assessed by the rate of removal of colloidal carbon. The Kupffer cells were prepared by a pronase/collagenase digestion method followed by elutriation. RESULTS: The phagocytic activity and production of glucose, lactate and pyruvate were reduced in cirrhotic livers when calculated per g liver. Due to hyperplastic-regenerative processes the mass of the cirrhotic livers was markedly augmented so that the colloidal carbon uptake calculated per cirrhotic liver was not significantly different from the controls. Colloidal carbon-induced glucose release increased more markedly in the controls than in cirrhotic livers. Isoproterenol considerably stimulated phagocytosis and glucose production in controls, whereas the response was clearly reduced in cirrhotic livers when calculated either per g liver or per total liver weight. The cyclic AMP analogue elicited a marked glycogenolytic response in the controls, whereas there was only a slight increase in glucose production in cirrhotic livers. Phagocytosis of cirrhotic livers was only moderately stimulated by opsonized zymosan when compared with the controls. Freshly isolated Kupffer cells exhibited a reduced phagocytic activity. Stimulation by zymosan was observed only in cell suspensions of the controls. In contrast, Kupffer cells from cirrhotic livers did not differ from controls with respect to basal or zymosan-stimulated phagocytic activity after 48-h cultivation. CONCLUSION: The stimulated phagocytic function was disturbed in perfused macronodular-cirrhotic livers as compared to controls. In contrast, 48-h cultured Kupffer cells from cirrhotic livers exhibited the same basal and stimulated phagocytic capacity as controls. The glucose release from perfused livers, initiated by stimulation of Kupffer cells or hepatocytes, was significantly reduced in cirrhotic livers. Therefore, we postulate an impaired intra- and/or intercellular signalling in macronodular-cirrhotic livers.

Animals↗

PubMed1997

Influence of age on the release of reactive oxygen species by phagocytes as measured by a whole blood chemiluminescence assay.

Polymorphonuclear and mononuclear phagocytes play an important role in host defense, but may also cause tissue injury through excessive inflammation. Reactive oxygen species (ROS) are not only directly ore indirectly involved in a wide variety of clinical disorders, such as atherosclerosis, reperfusion injury, pulmonary toxicity and cancer, but they are also important in the aging process. This process is associated with increasing susceptibility to infection. In this study we investigated the influence of age and sex on phagocyte activation by means of a whole blood chemiluminescence (CL) assay. Circulating phagocyte activity was measured in 55 healthy volunteers (24 females, 31 males) aged from 6 to 92 years. Using an automated luminescence system, phagocytes were stimulated by polystyrene beads and Luminol-enhanced CL was determined in terms of peak height and peak time in freshly withdrawn, peripheral venous whole blood. An extremely significant positive correlation (p < 0.0001) between the maximum of light emission after stimulation and increasing age was found. This finding is true for the total population of blood phagocytes as well as for a single cell. In contrast the time of the appearance of the maximum of light emission showed an extremely significant inverse correlation (p < 0.0003) with increasing age. The influence of sex on the CL-parameters showed no significant difference between women and men. It is concluded that the increased susceptibility of circulating phagocytes to oxidative burst in elderly subjects may be the consequence of several biological events. Senescent cells express more and also have new antigens on their surfaces that trigger an autoimmune response. Cellular senescence appears earlier in old organisms. Therefore phagocytes in aging individuals may be increasingly involved in their scavenger tasks that grow with the catabolic bias in cell turnover. Moreover, atherosclerotic alterations in the intima and endothelial lesions are physiologic concomitants of age and may lead to a stimulation of circulating phagocytes.

Adolescent↗

PubMed1983

Interactions of antibiotics and phagocytes.

Optimal therapy of infections due to organisms capable of surviving within phagocytes would include use of antimicrobials that penetrate phagocytic cells and inactivate intracellular organisms. To establish those characteristics of drug and cell that mediate the antibiotic-phagocyte interaction, we have studied the uptake of radiolabelled antibiotics by rabbit alveolar macrophages (AM), human AM from smokers and non-smokers, and human polymorphonuclear leukocytes (PMN). Relative entries of drug groups into the three types of phagocytic cells were similar. Penicillin G and cephalosporin antibiotics were taken up poorly by phagocytes. Lipid-soluble antibiotics, such as rifampicin and chloramphenicol, were concentrated several-fold (2-5) by phagocytes. Ethambutol, erythromycin and clindamycin were concentrated many-fold (5-50) by phagocytic cells. Human AM of smokers accumulated certain antibiotics more avidly than AM of non-smokers. Clindamycin entry into phagocytes was shown to be an active, energy-requiring process, mediated by the nucleoside transport system. Ingestion of microbial particles by PMN stimulated transport of both clindamycin and nucleoside (adenosine) into the cell.

Animals↗

PubMed2002

Inhibition of chemiluminescent response of olive flounder Paralichthys olivaceus phagocytes by the scuticociliate parasite Uronema marinum.

Experiments were conducted to evaluate the in vitro capacity of the scuticociliatian parasite Uronema marinum to inhibit chemiluminescence (CL) of olive flounder Paralichthys olivaceus phagocytes. Luminol-enhanced CL was used to measure the production of reactive oxygen intermediates (ROIs) generated by respiratory bursts of phagocytes using zymosan as a stimulant. Cytotoxic and antioxidative activities of excretory-secretory (ES) products of the parasite were evaluated as well. Live U. marinum and its ES products had a negative and dose-dependent effect on luminol-enhanced CL responses of zymosan-stimulated phagocytes of olive flounder. After CL assay, the number of phagocytes showing viability was significantly reduced in the cells incubated with live U. marinum at ratios of 2:1 and 1:1 phagocytes:ciliates or ES products with 0.3 mg protein ml(-1) compared to controls. Lysis of phagocytes by exposure to ES products was observed also. ES products from U. marinum showed considerably high activities of superoxide dismutase (SOD) and catalase. The results of this study suggest that U. marinum can protect itself against host's phagocytes mediated oxidative damage by destroying phagocytes and scavenging ROIs.

Animals↗

PubMed2000

Professional phagocytes: predators and prey of microorganisms.

Phagocytosis is an ancient cellular function. However, professional phagocytes have evolved only in higher organisms, where they play an important role in host defence. Professional phagocytes are capable of engulfing relatively large microorganisms and killing them with a combination of various microbicidal systems. Crucial killing mechanisms of phagocytes include superoxide generation by phagocyte NADPH oxidase and release of microbicidal proteins through exocytosis of performed granules. Phagocytes are also able to interfere with microbial growth through alteration of the phagosomal ionic environment (acidification, iron depletion). While the microbicidal mechanisms of phagocytes are extremely efficient and capable of killing most microorganisms, pathogenic microorganisms have developed mechanisms to resist phagocytes. Microorganisms capable of surviving within phagocytes are rare, but represent very successful pathogens, such as Mycobacterium tuberculosis. Other pathogens, such as S. aureus, have developed strategies to evade phagocytosis. How microorganisms are phagocytosed and killed, and why certain pathogens resist these mechanisms, are crucial questions for an understanding of the pathogenesis of infectious diseases and the development of innovative treatment approaches.

Humans↗

PubMed2002

Identification of subpopulations of bovine mammary-gland phagocytes and evaluation of sensitivity and specificity of morphologic and functional indicators of bovine mastitis.

The number and function of bovine mammary-gland phagocytes were assessed in 8 lactating cows, each tested at least twice within an 8-mo period (total number of observations, 20). Macrophages and polymorphonuclear (PMN) cells were evaluated by conventional cytology, flow cytometry, fluorescent microscopy, and somatic-cell count (SCC). Phagocytosis was evaluated from the uptake of fluorescent beads and expressed as median fluorescence intensity (MFI). Two major subpopulations of phagocytes, of low or high MFI (LFI or HFI), were observed, and there were up to 4 sub-subpopulations within the HFI subpopulation of both macrophages and PMN cells. Fluorescent microscopy identified phagocytes containing up to 4 beads per cell. Cows showing < or = 72.3% phagocytes by cytology were regarded as non-mastitic (11 observations), and those showing > or = 80.7% phagocytes were considered to be mastitic (8 observations). Phagocyte MFI was negatively associated with mastitis; that is, the higher the MFI, the lower the SCC. The percentage of HFI PMN cells was the only indicator of mastitis with 100% sensitivity and specificity. Thus, bovine mammary-gland phagocytes consist of several subpopulations of different phagocytic ability, whose assessment more adequately predicts bovine mastitis than do morphologic indicators.

Animals↗

PubMed1989

Lyt-2+ T cell-mediated protection against listeriosis. Protection correlates with phagocyte depletion but not with IFN-gamma production.

The transfer of listeria-immune splenocytes into non-immune mice markedly increases host resistance to listeriosis. To study the mechanism for this enhancement, we compared the inflammatory response to infection in nonimmune and adoptively immunized mice. Despite much better containment of bacterial growth, adoptively immunized animals accumulated significantly fewer phagocytes (neutrophils and macrophages) in the spleen and liver than controls. Immune T cells not only inhibited phagocyte accumulation but also reduced the in vitro anti-listerial activity of splenocytes. Significant differences in phagocyte accumulation were observed even when the initial listeria dose was adjusted to produce comparable spleen listeria loads in immune and non-immune animals. However, bone marrow and peripheral blood phagocyte counts were similar in both groups. Depletion of Lyt-2+ cells (using mAb and C) from donor splenocytes prevented the transfer of protection and increased phagocyte accumulation without altering listeria-dependent IFN-gamma production by donor or recipient splenocytes in vitro. L3T4 depletion did not affect host resistance or phagocyte accumulation even though it reduced in vitro interferon production by donor cells. Hence the different effects of L3T4+ and Lyt-2+ cells in vivo cannot be explained simply by variations in IFN production. We suggest this paradoxical suppression of phagocyte accumulation during adoptive transfer may reflect lysis of bacteria-laden phagocytes by listeria-specific Lyt-2+ cells in vivo. Selective destruction of older, heavily infected cells might contribute to host resistance by eliminating a potential site for intracellular proliferation of bacteria.

Animals↗

PubMed1987

Differential antimicrobial activity of human mononuclear phagocytes against the human biovars of Chlamydia trachomatis.

The antimicrobial activities of human mononuclear phagocytes against Chlamydia trachomatis were investigated. Phagocytes cultured for 7 days or less were efficiently microbicidal. Almost complete inactivation of organisms from both human biovars was observed after 48 hr of incubation. However, organisms from the lymphogranuloma venereum (LGV) biovar survived in mononuclear phagocytes infected after 8 days or more in culture, whereas those from the trachoma biovar continued to be killed by such cells. Phagocytes cultured as long as 21 days killed the trachoma organisms with the same effectiveness as those cultured for 7 days or less. An ultrastructural study of inoculated phagocytes illustrated phagolysosomal fusion with degradation of organisms from either biovar in phagocytes which had been cultured for 24 hr before infection. Phagolysosomal fusion was not observed in cells which had been cultured for 8 days or more and then infected with LGV. The addition of interferon-gamma to these macrophages partially restored the phagocytes' microbicidal activity for LGV. Furthermore, a synergistic effect was observed when eosinophil peroxidase was added with interferon. Specific antibody failed to neutralize the infectivity of LGV organisms in 8-day or older mononuclear phagocytes. The findings may reflect the differences in disease syndromes between the two biovars, with the trachoma biovar causing more peripheral diseases and the LGV biovar causing a more systemic disease, with lymph node involvement as its main syndrome.

Blood Bactericidal Activity↗

PubMed1995

Characterization of the cytolytic trigger molecules G7/PNK-E as a molecular complex on the surface of porcine phagocytes.

G7 and PNK-E mAbs recognize distinct porcine NK cell and granulocyte function-associated molecules that enhance and induce a significant cytolytic response against tumor cell targets through a mechanism of re-directed cytotoxicity. The present study shows that the G7 and PNK-E molecules are present on the surface of porcine neutrophils, monocytes, and pulmonary alveolar macrophages as a physically and functionally associated cytolytic trigger molecular complex. Two-color flow cytometric analysis demonstrates that most, if not all, neutrophils are G7 and PNK-E antigen positive. In contrast, monocytes and PAM contain both G7 and PNK-E positive as well as G7 positive and PNK-E negative subpopulations. mAb binding competition experiments indicate that pretreatment of phagocytes with G7 mAb can block subsequent binding by PNK-E mAb, suggesting that these antigens are physically associated on the surface of porcine phagocytes. Fluorescent co-capping experiments utilizing G7 and PNK-E mAbs clearly demonstrate a physical association between G7 and PNK-E antigens present on the surface of porcine neutrophils. Pretreatment of phagocytes with F(ab')2 fragments of G7 and PNK-E mAbs shows that F(ab')2 G7 mAb blocks subsequent induction of phagocyte-mediated tumor cell cytotoxicity by whole PNK-E mAb but pretreatment with F(ab')2 PNK-E does not block subsequent induction of phagocyte-mediated tumor cell cytotoxicity by whole G7 mAb. In addition, pretreatment of neutrophils and mononuclear phagocytes with F(ab')2 fragments of G7 mAb blocks subsequent whole PNK-E mAb-dependent activation of a phagocytic cell intracellular oxidative burst response but pretreatment with F(ab')2 PNK-E does not block subsequent G7 mAb-dependent activation of a phagocytic cell intracellular oxidative burst response. These data reinforce a physical and functional association between the G7 and PNK-E molecules. Recent identification of the G7 antigen as the porcine homolog of Fc gamma RIII indicates that the G7 and PNK-E mAbs recognize a unique and previously uncharacterized Fc gamma R cytolytic trigger molecular complex present on the surface of porcine neutrophils, monocytes, and PAM.

Animals↗

PubMed2000

Phagocytic activities of the gorgonian coral Swiftia exserta.

The cellular response component of body defense in gorgonians and other cnidarians is thought to be carried out by cells with phagocytic capabilities. To test for the phagocytic character of cells, the introduction of foreign particles was employed and observed in both living cells and histological preparations of the gorgonian coral Swiftia exserta. Observations of untreated tissues revealed normal cells and tissue morphologies. A microscopic observation of living cells following the introduction of particles in a cut revealed that only a mixed population of colorless cells phagocytized the particles. Also particles or clumps of particles were seen on the surface of the colorless cells. Subsequent histological observations allowed identity of colorless cells to be inferred as granular amoebocytes, ectodermal cells, and gastrodermal cells. Cells stained for localization of peroxidase (indicative of phagocytic activity) demonstrated the presence of peroxidase-positive cells. Histological preparations revealed that major phagocytosis of particles was associated with tissue trauma. When particles were introduced by means of a cut or inserted thread, phagocytic activity was detected within 2 h. However, it was confined to the granular amoebocytes in the immediate site of trauma. After 24 h, extensive phagocytosis spread throughout a relatively large area surrounding the wound. At that later time, phagocytic cell types included granular amoebocytes, epidermal cells, sclerocytes, mesogleal cells, and gastrodermal cells of the solenia. Observations suggest that trauma induces phagocytosis in cells not normally phagocytic in S. exserta. No localization of phagocytic cells and no mitotic cells were observed at either 2 or 24 h after particle introduction.

Animals↗

PubMed1990

Effect of phagocytosis of erythrocytes and erythrocyte ghosts on macrophage phagocytic function and hydrogen peroxide production.

Our previous studies have shown that an in vivo phagocytic challenge with IgG-coated erythrocytes can depress Kupffer cell complement and Fc receptor function, as well as decrease the survival rate following endotoxemia and bacteremia. In an effort to better understand the mechanism underlying these in vivo findings, the present study evaluated the in vitro effects of a phagocytic challenge with either IgG-coated erythrocytes (EIgG) or erythrocyte ghosts (GIgG) on macrophage phagocytic and respiratory burst activity. Elicited rat peritoneal macrophage (PM) monolayers were challenged with varying doses of EIgG, then the noninternalized EIgG were lysed hypotonically and the monolayers incubated for an additional hour prior to determining phagocytic function and PMA-stimulated hydrogen peroxide production. Challenge of PM with 1 x 10(6) EIgG per well had no effect, but challenge with 1 x 10(7) or 1 x 10(8) EIgG per well caused a dose-dependent depression of phagocytic function or hydrogen peroxide production. GIgG were formed by hypotonically lysing EIgG bound to PM at 4 degrees C. The bound GIgG were phagocytized during a subsequent incubation at 37 degrees C. Challenge with GIgG depressed phagocytic function only with the highest challenge dose tested (1 x 10(8) per well) and did not depress hydrogen peroxide production. The observation that prior phagocytic challenge with EIgG depressed macrophage function to a greater extent than challenge with GIgG supports our previous in vivo observations. Furthermore, these studies suggest that the internalization of erythrocyte contents, and not phagocytosis per se, plays an important role in determining macrophage host defense function.

Animals↗