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PubMed1989

Are glycoconjugates and their endogenous receptors involved in the fusion of mononuclear macrophages resulting in multinucleate giant cells? Histochemical and electron microscopic determination of endogenous sugar-binding proteins (lectins) in mononuclear macrophages and multinucleate giant cells appearing in granulomatous foreign body reaction.

Protein-carbohydrate recognition has been found to play an important role in phagocytosis. Labelled (neo)glycoproteins were employed to comparatively analyze the histochemical pattern and ultrastructural localization of endogenous carbohydrate-binding proteins (lectins) of mononuclear macrophages and multinucleate giant cells involved in the granulomatous foreign body reaction. Sugar receptors having an affinity to simple alpha- and beta-galactoside-structures, to alpha-mannose residues, to N-acetylglucosamine, to N-acetylgalactosamine and to glucuronic acid, respectively, were detected in both cell types. However, alpha-fucoside- and beta-xyloside-specific receptors were present only in the mononuclear macrophages. Pronounced differences were seen with labelled, suitably modified glycoproteins, exposing different complex sugar parts with common beta-galactoside-termini. Among the population of multinucleate giant cells, a positive histochemical reaction was observed with mannose-6-phosphate-, galactose-6-phosphate- and glucuronic acid-(BSA-biotin), respectively, only in giant cells in which fusing mononuclear cells were recognizable. This transient expression indicates changes within the profile of endogenous sugar receptors in the stages from fusion to establishment of giant cells. Aside from the diffuse intracytoplasmic distribution of carbohydrate-binding proteins, a prominent accumulation of various types of glycosylated ferritin, used as a marker for electron microscopic evaluation, was ultrastructurally found in membranous subcellular structures and vesicles. This study is a basis for further investigation of the potential involvement of various sugar receptors in the process of macrophage fusion, resulting in multinucleate giant cells of foreign body type, and the process of phagocytosis.

Biopsy↗
PubMed1986

The interactions between macrophages and developmental stages of Schistosoma mansoni: effect of macrophage function modulators on the viability of S. mansoni in vivo and in vitro.

ICR mice infected with Schistosoma mansoni developed sizable concomitant immunity to a challenge infection 10 weeks, but not 7 weeks, following the primary infection. At 7 weeks, postprimary-infection mice exhibited increased resistance to reinfection when treated with BCG or MDP. BCG even rendered noninfected mice resistant to infection. Macrophage function inhibitors such as silica and trypan blue did not abolish the concomitant immunity state, but they increased the worm burden due to a single infection, whether given before or after the infection. The onset of concomitant immunity in infected mice was paralleled by the appearance in their peritoneal exudate of schistosomulicidal-adherent macrophages. Such cells were evident at 9 but not 7 weeks of infection. The in vivo injection of MDP accelerated their appearance in infected mice, while silica, trypan blue, and carrageenan abolished it. The findings suggest that highly activated schistosomulicidal macrophages develop in infected mice, and might participate in the destruction of the invading parasite.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Stimulation by granulocyte-macrophage colony-stimulating factor of Leishmania tropica killing by macrophages.

The intracellular protozoan parasite Leishmania tropica was found to survive unharmed and to multiply for several days in normal mouse peritoneal macrophages. In contrast, when infected monolayers were treated with GM-CSF, there was a continuous decrease in the percentage of infected cells, reaching less than 10% on day 4 in culture, compared to about 30% in normal controls. Microscopic observations showed an increased number of dead parasites in GM-CSF treated infected cells. Within 5 hr of incubation with GM-CSF, almost 40% of intracellular parasites showed morphologic damage, compared to less than 10% in untreated cells. Pretreatment of macrophage monolayers with pure GM-CSF before infection led to an increased level of phagocytosis of L. tropica parasites as reflected by the percentage of infected cells and the increased number of parasites in each infected cell. GM-CSF treated cultures showed 73% infected cells containing a mean of five parasites per cell, as compared to controls in which only about 50% of macrophages were infected with only two parasites per cell. The number of dead parasites per cell was 5-fold higher in the GM-CSF treated cultures at 2 hr. After 24 hr the percentage of infected GM-CSF treated cells was less than one-third that in the control cultures.

Animals↗
PubMed1979

The role of macrophages in leprosy as studied by protein synthesis of macrophages from resistant and susceptible hosts--a mouse and human study.

3H-leucine uptake by macrophages from swiss white and C57BL mice before and after M. leprae infection was studied. A depression in 3H-leucine uptake after infection was observed only in swiss white mice. 3H-leucine uptake was also studied in blood derived macrophages from normals, and LL and TT patients. A depression was obtained in 3H-leucine uptake after M. leprae infection in macrophages from LL patients.

Animals↗
PubMed1975

Macrophage-lymphocyte interaction: antigen-independent binding of guinea pig lymph node lymphocytes by macrophages.

The antigen independent binding of guinea pig lymph node lymphocytes by glass-adherent macrophages was investigated. Binding was found to be mediated by a trypsin digestible, divalent cation-dependent, temperature-sensitive macrophage receptor mechanism that was not competitively inhibited by excess immunoglobulin. Data are presented to indicate that in the absence of antigen, macrophages were capable of binding both thymus-derived and bone marrow-derived lymphocytes without apparent selectivity, and further, that the binding of neither cell was mediated by surface membrane-associated immunoglobulin.

Animals↗
PubMed1983

The use of frozen erythrocytes in macrophage studies. 2. Attachment and phagocytosis mediated by the two immunological receptors of the macrophages.

Sheep erythrocytes opsonized with IgG or C3b were frozen in various cryoprotective agents, thawed, and compared to corresponding unfrozen erythrocytes exposed to the cryoprotectants and to unfrozen erythrocytes not exposed to the cryoprotectants (controls) as test particles in macrophage attachment and phagocytosis assays. Fc-receptor-mediated attachment and phagocytosis were not influenced by the use of any cryoprotective agent tested or by freezing the erythrocytes. This was also the case with C3b-receptor-mediated attachment. Phagocytosis via this receptor was negligible in normal macrophages, but tended to be slightly more effective when the test particles had been treated with cryoprotective agents. In vitro stimulation of the macrophages with Escherichia coli endotoxin, however, triggered the capacity to internalize treated and untreated erythrocytes equally.

Animals↗
PubMed1981

Origin of crystalloid inclusions in macrophages I: studies of peritoneal macrophages after erythrocyte ingestion.

In an attempt to investigate the origin of crystalloid inclusions present in bone-marrow macrophages of normal adult mice and in man, murine peritoneal macrophages (which normally do not contain inclusions of this nature) were studied by light and electron microscopy 24 h after 3 daily injections of various preparations of erythrocytes. The preparations included mouse erythrocytes with and without pretreatment with collagenase, human erythrocytes and human-erythrocyte ghosts. Crystalloid inclusions were only rarely seen in the peritoneal macrophages in these circumstances. The results offered little support for the idea that crystalloid inclusions are derived from the breakdown of erythrocytes.

Animals↗
PubMed1984

Macrophage function in the Schistosoma mansoni egg-induced pulmonary granuloma. Role of arachidonic acid metabolites in macrophage Ia antigen expression.

The ability of arachidonic acid (AA) metabolites to regulate I-region-associated (Ia) antigen expression on macrophages from schistosome-egg-induced pulmonary granulomas was examined. The prostaglandin (PG) analog 15-S-15-CH3-PGE1 (M-PGE1) and PGF2 alpha were found to modulate the kinetics of Ia expression when administered in vivo. Methyl-PGE1 significantly suppressed Ia antigen expression by hypersensitivity granuloma macrophages, while PGF2 alpha appeared to potentiate the expression. Lymphokine-induced Ia antigen expression by cultured granuloma macrophages was likewise dramatically inhibited by M-PGE1. Further analysis using systemically administered inhibitors of AA metabolism demonstrated that the cyclooxygenase inhibitor indomethacin caused augmentation of Ia expression. In contrast, lipoxygenase inhibitors significantly reduced both Ia expression and granuloma size. The role of AA metabolites in modulating chronic inflammation is discussed.

Alprostadil↗
PubMed1983

Interaction of latex-insolubilized endotoxins with murine macrophages: phagocytic responses of endotoxin-responsive (C3HeB/FeJ) and -unresponsive (C3H/HeJ) macrophages in vitro.

Insolubilized lipopolysaccharides (LPS) were prepared by covalently coupling LPS from polysaccharide-deficient S. minnesota R595 and polysaccharide-rich E. coli 055:B5 to carboxylated latex particles. The stability of these LPS-latex complexes was determined using several assays to detect soluble LPS following incubation at ambient and elevated temperatures. Resident and thioglycollate-elicited macrophages from both LPS-responder C3HeB/FeJ and LPS nonresponder C3H/HeJ mice were examined for their capacity to phagocytose the LPS particles following in vitro culture for various time periods. Uptake was demonstrated by an increase in the number of particles within the macrophages with increasing time of incubation. Rough polysaccharide-deficient LPS-latex particles were found to be more readily phagocytosed than control particles, whereas smooth polysaccharide-rich LPS particles were phagocytosed less readily than the controls. Qualitatively similar results were found in the relative rate of uptake of particles by the macrophages from the endotoxin-responsive and -unresponsive mouse strains used in this study.

Animals↗
PubMed1980

Regulatory role of humoral factors released by macrophages in rat lymphocyte reactivity in vitro. II. Influence of humoral factors released by normal peritoneal macrophages on spontaneous lymphocyte stimulation.

Supernatants harvested from peritoneal macrophage cultures, derived from normal rats, exhibit in vitro two antagonistic activities: stimulating and suppressing spontaneous stimulation of syngeneic lymphocytes. Stimulation of DNA synthesis by macrophage supernatants occurs in lymph node lymphocytes, which show low values of spontaneous stimulation. Suppression of DNA synthesis by macrophage supernatants is revealed in thymocytes and cortisone-resistant thymocytes, which demonstrate high values of spontaneous stimulation.

Adjuvants, Immunologic↗
PubMed1978

Pathogenicity of equine herpesvirus: in vivo persistence in equine tissue macrophages of herpesviuus type 2 detected in monolayer macrophage cell culture.

Equine macrophages from the mammary glands of a yearling filly and an 18-year-old barren nonlactatind mare formed cell monolayers in continuous cultures. There was absence of viral cytopathic effect (CPE) in early cell culture passages. The cells from the early cell culture passages having no CPE failed to show evidence of virus or viral antigen by electron microscopic and immunofluorescence studies. Foci of CPE first appeared in the monolayer cell cultures from the filly and the mare in the 3rd and the 4th serial passages respectively, and the CPE increased on subsequent serial passages. Equine herpesvirus type 2 (EHV 2) cultures showing CPE. The macrophage monolayer culture established from the mare produced CPE foci more consistently than did the culture from the filly, and they were more numerous. Conversely, the peripheral blood mononuclear cells from the filly on cocultivation with an equine embryo kidney monolayer cell culture produced more EHV 2 CPE foci than did those from the mare. This study indicated that tissue macrophages may be a site for latent and persistent herpesvirus infections in horses.

Age Factors↗
PubMed1981

Macrophages in resistance to rickettsial infections: characterization of lymphokines that induce rickettsiacidal activity in macrophages.

Lymphokine-rich culture supernatants of antigen- or mitogen-stimulated spleen cells were fractionated by Sephadex G-200 column chromatography; fractions were assayed for capacity to induce tumoricidal and rickettsiacidal activities in mouse macrophages. Lymphokine activity that activated macrophages for tumor cytotoxicity eluted as a single peak in the 45,000 m.w. region. In contrast, activity for intracellular killing of rickettsiae eluted in 3 distinct regions: 115 to 125,000, 35 to 45,000, and less than 10,000 daltons. This elution pattern was observed with both antigen and mitogen-induced lymphokines. Activity of each of the 3 lymphokine species for induction of rickettsiacidal activity was destroyed by heating at 56 degrees C for 1 hr. Tumor cytotoxicity and rickettsiacidal activity, both effector functions of activated macrophages, were dissociated on the basis of lymphokines regulating these activities.

Animals↗
PubMed1980

Role of macrophages in defective cell mediated immunity in lepromatous leprosy. I. Factor(s) from macrophages affecting protein synthesis and lymphocyte transformation.

Macrophages from lepromatous leprosy patients specifically show reduced protein synthesis in the presence of M. leprae. They also produce, as a result of interaction with M. leprae, factor(s) that reduce protein synthesis in normal macrophages as well as block lymphocyte transformation in normal leukocyte cultures in the presence of M. leprae as the antigen. These observations implicate a defective macrophage system in lepromatous leprosy patients.

Cells, Cultured↗
PubMed1978

Comparative effects of Corynebacterium parvum, Brucella abortus extract, Bacillus Calmette-Guérin, glucan, levamisole, and tilorone with or without cyclophosphamide on tumor growth, macrophage production, and macrophage cytotoxicity in a murine mammary tumor model.

In this laboratory, it has been repeatedly demonstrated (using a murine mammary tumor model) that the combination of cyclophosphamide (CY) and Corynebacterium parvum (CP) is more effective than either agent alone in the control of tumor growth. This paper presents information obtained in our model comparing findings on the effects of CP with a Brucella abortus extract (Bru-Pel; BP) and glucan (GL) on tumor growth. In addition, the influence of those agents as well as bacillus Calmette-Guérin, tilorone, and levamisole on bone marrow macrophage colony production and cytotoxicity is presented. None of the nonspecific stimulating agents (NSSAs) inhibited tumor growth when administered systemically without CY, confirming our previous contention that such immunotherapy alone is likely to be an ineffectual form of treatment. Whereas tumor regression was observed following intratumor CP, neither GL nor BP had such an effect. When used with CY, neither BP nor GL administered ip or intratumorally inhibited tumor growth as effectively as did CP and CY. Inhibition of the growth of a distant tumor as well as the treated tumor occurred following intratumor CP and CY but not following intratumor BP and CY. All of the microbial NSSAs increased macrophage colony production to varying degrees in both normal and tumor-bearing mice. In the latter mice, CP had the most prolonged effect. Levamisole and tilorone failed to increase colony production in normal mice while in tumor-bearing mice the effect was inversely proportional to the amount of agent administered. To some extent, the stimulation of colony production by the NSSAs paralled the degree of tumor inhibition observed when those agents were combined with CY. The cytotoxicity of cultured macrophages could not be related to tumor growth inhibition.

Animals↗
PubMed1980

Characterization of a human macrophage-like cell line stimulated in vitro: a model of macrophage functions.

When cells of human macrophage-like cell line U937 are cultured in the presence of medium conditioned by mixed lymphocyte culture (MLC), PHA- or Con A-stimulated lymphocytes they demonstrate morphologic and functional characteristics of stimulation. The cells become larger, their surface more villous, and the cytoplasm has increased numbers of lysosomes and phagosomes. There is a marked (at least 10-fold) increase in antibody-dependent cellular cytotoxicity (ADCC) against both erythroid and tumor targets accompanied by increased expression of Fc receptors (FcR). There is also an augmentation of antibody-dependent phagocytosis. Medium conditioned by unstimulated lymphocytes, a B lymphoblastoid cell line or a fibroblast cell line produce very little stimulation of U937 cells. U937 cells gradually lose their increased ADCC capacity if they are washed free of conditioned medium (CM) but can be maintained in a stimulated state for long periods of time by culturing them in medium supplemented with PHA-CM at a concentration of 2%. Stimulation of macrophage-like cell line U937 may provide a useful model for further study of mechanisms of macrophage cytotoxicity and its modulation by products of activated lymphocytes.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1995

RAW264 macrophages stably transfected with an HIV-1 LTR reporter gene provide a sensitive bioassay for analysis of signalling pathways in macrophages stimulated with lipopolysaccharide, TNF-alpha or taxol.

Bacterial lipopolysaccharide (LPS) modulates expression of a variety of genes in macrophages, and additionally activates viral promoters including the HIV-1 LTR. The HIV-1 LTR driving the luciferase reporter gene was stably transfected into the murine macrophage cell line, RAW264. In stably transfected cells, luciferase activity was LPS-dependent. As little as 0.01 ng/ml LPS was sufficient to increase luciferase activity over basal levels with maximal stimulation resulting in a 10- to 20-fold response. The cells also responded to human and murine tumour necrosis factor (TNF alpha). Endogenous TNF alpha was not involved in LPS responses, since pretreatment with alpha-TNF alpha antibody did not affect activation. Induction of HIV-1 LTR activity by LPS occurred independently of phorbol myristate acetate (PMA) sensitive protein kinase C (PKC), since depletion of PKC by prolonged exposure to PMA blocked TNF alpha and PMA responses but was not able to abolish LPS action on these cells. Taxol (5-20 micrograms/ml), a chemotherapeutic agent which mimics LPS action on macrophages, was also able to increase expression of the reporter gene driven by the HIV-1 LTR. However, lower doses of taxol that were not sufficient to trans-activate the LTR or to induce TNF alpha expression were cytotoxic to RAW264 cells suggesting that the cytotoxic and LPS-like activities of taxol were not linked. This cell line provides a convenient method for detecting LPS-like activity and is a useful tool for examining LPS and TNF alpha signalling pathways.

Animals↗
PubMed1993

Macrophage-dependent candidacidal mechanisms in the murine system. Comparison of murine Kupffer cell and peritoneal macrophage candidacidal mechanisms.

Candida albicans infection is common in immunocompromised patients. The role of fixed tissue macrophages (M phi), including Kupffer cells (KC) and peritoneal macrophages (PM phi), in host defense against C. albicans is unclear. This study examined murine M phi candidacidal mechanisms and evaluated the in vitro role of the macrophage-activating factor IFN-gamma in augmenting these mechanisms. The effect of in vivo administration of IFN-gamma on survival after lethal C. albicans challenge in the murine system was also assessed. Percent PM phi and KC ingestion of C. albicans were similar. Prior opsonization of Candida increased the percentage of M phi ingestion of this pathogen. PM phi and KC phagocytic function was similar for both nonopsonized and opsonized C. albicans, but KC demonstrated markedly decreased ability to kill this pathogen (O2-, Candida killing). IFN-gamma enhanced KC and PM phi candidacidal activity. PM phi and KC Ag presentation was increased in early Candida infection, but diminished in established infection, when the majority of animals died. C. albicans failed to elicit significant amounts of either IL-1 or TNF compared with LPS stimulation of PM phi and KC in vitro. IFN-gamma treatment in vivo was associated with significantly improved survival (p < 0.01).

Animals↗
PubMed1995

The effect of activated alveolar macrophages on experimental lung emphysema development. II. The study of fibroblast and alveolar macrophage co-culture.

The cell-cell interaction between fibroblasts and alveolar macrophages was examined using a co-culture system. Alveolar macrophages (AM) were harvested from the bronchoalveolar lavages (BAL) of rats with papain induced lung emphysema. The BCG-vaccine was applied as a macrophage mobilizing and activating agent. The morphological examinations carried out in scanning electron microscope (SEM) as well as the evaluation of the uptake of 3H-thymidine did not show any significant differences between respective co-cultures of fibroblasts and AM isolated both from the lungs of control and experimental animals (treated with BCG or papain, and BCG+papain). However, significant growth were noted in 3H-thymidine uptake between fibroblast cultures done with or without cells isolated from the lungs. The results obtained suggest that AM can promote fibroblast proliferation during the progression of experimental lung emphysema.

Animals↗