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PubMed1995

The effect of free and liposome-encapsulated clodronate on the hepatic mononuclear phagocyte system in the rat.

Clodronate, encapsulated within small unilamellar vesicles (SUVc) will deplete hepatic macrophages after intravenous injection. Functional studies, using probes to evaluate hepatic Fc and C3b uptake, showed a close correlation between the inhibition of receptor-mediated uptake and the depletion of hepatic macrophages. Twenty milligrams of clodronate encapsulated within SUVc produced > or = 90% inhibition of uptake and clearance of Fc- and C3b-coated erythrocytes and a comparable reduction of hepatic macrophage numbers. Inhibition of macrophage receptor-mediated uptake of these erythrocytes was closely related to the reduction in macrophage numbers. Repopulation of macrophages within the liver took place over 2 weeks. At 1 week after depletion, although repopulation was taking place, receptor-mediated function remained suppressed. In a preliminary experiment, treatment of rats with adjuvant arthritis with 20 mg clodronate encapsulated in SUV suppressed the inflammation and reversed the course of the disease, while treatment with 20 mg free clodronate in saline or 20 mg clodronate in multilamellar vesicles (MLVc) did not.

Animals↗
PubMed1983

Complement (C3) receptor-mediated attachment of agarose beads to mouse peritoneal macrophages and human monocytes.

We have determined the receptors on human monocytes and mouse peritoneal macrophages producing agarose binding. By using isolated human complement factors C3, B and D, agarose beads were coated with C3b. In some experiments C3b was converted to C3bi by using human serum diluted 1:20. Agarose beads coated with C3b or C3bi bound strongly to monocytes. Only agarose beads coated with C3bi were attached to mouse macrophages. Trypsinization of agarose beads coated with C3bi abolished the attachment of the beads to macrophages and monocytes, probably because of conversion of C3bi to C3d. Endocytosis by macrophages of agarose preincubated in human serum or in C5-deficient AKR mouse serum reached the same levels, indicating that the amount of C5 present in serum during preincubation is not important for the degree of endocytosis. It is concluded that internalization of agarose by macrophages is mediated via the C3bi receptor.

Animals↗
PubMed1984

C3 cleaved by membrane proteases binds to C3b acceptors expressed on concanavalin A-stimulated human lymphocytes and enhances antibody-dependent cellular cytotoxicity.

On activation of cells membrane-associated proteases--including serine esterases known to cleave the third component of complement (C3)--become expressed. In this paper it is shown that as a consequence of this enzyme activity isolated native human C3 added to concanavalin A (Con A)-activated human lymphocytes is cleaved on the surface of the blast cells. This enables the immediate fixation of nascent C3b (C3bx) through its short-lived metastable binding site to C3b acceptors (C3bA's) newly expressed on Con A-stimulated cells. Acceptor-bound C3b is detected by the immune adherence rosette formation of the C3-treated Con A blasts with the C3b receptor (C3bR)-bearing O, Rh+ erythrocytes (32 +/- 4%). The cleavage of C3 and the covalent fixation of C3b are shown to be inhibited by phenylmethylsulphonyl fluoride and methylamine, respectively. As a functional consequence of the covalent fixation of C3b to the mitogen-activated lymphocytes it is demonstrated that the antibody-dependent cellular cytotoxicity (ADCC) of these cells against O, Rh+ erythrocytes sensitized with anti-D IgG is significantly enhanced. The C3 specificity of the process and the role of C3bR's of the target cells are proved. It is postulated that effector cell-bound C3b amplifies ADCC by improving effector cell-target cell contact.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1984

Effects of interferon-alpha/beta and interferon-gamma preparations on phagocytosis by mouse peritoneal macrophages.

The influence of murine alpha/beta-interferon (Mu IFN-alpha/beta) and murine gamma-interferon (Mu IFN-gamma) preparations on the attachment and ingestion phase of phagocytosis by mouse peritoneal macrophages (MPM) was studied. A non-opsonized strain of Escherichia coli, IgG-opsonized E. coli, and sheep erythrocytes opsonized with IgG (E-IgG) and IgM plus complement factor C3b (E-IgMC) were used as test particles. Pretreatment of MPM with 10(2)-10(3) U/ml of Mu IFN-alpha/beta for 24 h enhanced both attachment and ingestion of bacteria or erythrocytes mediated by the non-specific receptor, the Fc receptor, or the C3b receptor. Higher concentrations had no such effects. In contrast, treatment of MPM with 10(1)-10(2)U/ml of Mu IFN-gamma suppressed attachment and ingestion of non-opsonized and IgG-opsonized E. coli and of E-IgG by 10-40%. Mu IFN-gamma did not influence attachment and ingestion of E-IgMC. The effects were neutralized by specific anti-IFN antiserum. The data indicate that the IFN effect on phagocytic activity is, at least to a large extent, due to modifications of the surface receptors.

Animals↗
PubMed1984

Variations in expression of markers by populations of adherent cells from Trypanosoma cruzi-infected mice.

The kinetics of differentiation and maturation of phagocytic cells during the acute and chronic stages of experimental Chagas' disease was examined by monitoring changes in expression of peroxidase (PO), nonspecific esterase (NSE), C3b receptors (CR), Fc receptors (FcR), and phagocytic ability of cells in the blood, spleen, and peritoneal cavity. The significant changes recorded in the blood were: marked increases in the percentages of CR- and FcR-positive adherent cells during both the acute and chronic phase; Ia-positive cells increased two-fold in the acute period and remained elevated in the chronic stage. In the spleen, the major alterations recorded during both the acute and chronic stages were: two- to three-fold increases in the percentages of NSE- and PO-positive adherent cells and three- to four-fold increases in the proportions of CR- and FcR-positive cells. In addition, Ia-positive cells increased from 70% to approximately 90% of the adherent cell population. In the peritoneal cavity, a two- to four-fold elevation in the percentages of both PO- and NSE-positive cells was observed. The number of Ia-positive cells increased from 10% before infection to 85-90% during the acute phase and to 96-98% during the chronic period. All of the changes described above occurred in the absence of noticeable increases in phagocytic ability except for an elevation in the percentage of circulating latex-ingesting cells seen during chronicity. These results indicate that infection with Trypanosoma cruzi alters the pathways of differentiation of cells of the mononuclear phagocyte lineage.

Animals↗
PubMed1996

Interleukin-10 inhibits neutrophil phagocytic and bactericidal activity.

Effective host defense against bacterial invasion is characterized by the vigorous recruitment and activation of inflammatory cells, which is dependent upon the coordinated expression of both pro- and anti-inflammatory cytokines. Interleukin-10 (IL-10) is a recently described cytokine with potent anti-inflammatory properties in vivo and in vitro. In this study we investigated whether IL-10 could directly regulate the ability of neutrophils (PMN) to phagocytose and kill bacteria. Initial studies demonstrated that human recombinant IL-10 (hrIL-10) inhibited the ability of PMN to phagocytose Escherichia coli in vitro. Inhibition of phagocytosis occurred in the absence of changes in CR1 (C3b) or Fc receptor expression, as treatment of PMN with IL-10 failed to induce significant changes in Fc gamma IIR, Fc gamma IIIR or CR1 cell surface expression. However, incubation of PMN with IL-10 resulted in a dose-dependent decrease in CDIIb (Mac-1) expression. In addition to effects on PMN phagocytosis, hrIL-10 significantly attenuated PMN microbicidal activity, as bactericidal assays revealed that co-incubation of PMN with hrIL-10 resulted in a marked decrease in killing of phagocytosed bacteria. Furthermore, IL-10 inhibited the production of superoxide from PMA-stimulated PMN, suggesting that the detrimental effects of IL-10 on PMN microbicidal activity were due, in part, to suppression of respiratory burst. In summary, our studies indicate that IL-10 inhibits PMN-dependent phagocytosis and killing of E. coli in vitro, and suggest that this cytokine may impair effective antibacterial host defense in vivo.

Complement C3b↗
PubMed1998

Soluble mannan and beta-glucan inhibit the uptake of Malassezia furfur by human monocytic cell line, THP-1.

The uptake of live and heat-killed Malassezia furfur HIC 3321, HIC 3343 and Candida albicans ATCC 10231 by human monocytic cell line, THP-1, was examined. THP-1 was differentiated by PMA for 7 days before use. The uptake of these yeasts by THP-1 was increased in a concentration-dependent manner of yeasts, and the uptake reached plateau level at the E/T (yeast/THP-1) ratio 5. In addition, a higher percentage of heat-killed cells than live cells was taken in THP-1. Yeast mannan and beta-1,3-glucan, random coiled conformer, inhibited the uptake of live and heat-killed M. furfur by THP-1, though dextran T-250, that is alpha-glucan, and schizophyllan (SPG), triple helix conformer of beta-glucan, did not. Interestingly, mannan inhibited the uptake of both types, live and heat-killed, of C. albicans, however, laminaran inhibited the uptake of heat-killed C. albicans alone. Opsonization of these yeasts with normal human serum enhanced the uptake of yeasts, although opsonization with heat-inactivated serum, the treatment at 56 degrees C for 30 min, did not enhance. These results suggested that live and heat-killed M. furfur was recognized by THP-1 through mannose receptor, beta-glucan receptor and complement receptor type 3 via the activation of alternative pathway of complement.

Candida albicans↗
PubMed1996

Increased release of free oxygen radicals from peripheral neutrophils in adult periodontitis after Fc delta-receptor stimulation.

The release of free oxygen radicals and degranulation was studied in neutrophils from 14 patients with adult periodontitis and 14 age- and sex-matched healthy controls. The neutrophils were activated by Fc gamma-receptor stimulation, using Staphylococcus aureus opsonized with gamma globulin. Release of oxygen radicals was measured as luminol-enhanced chemiluminescence. Degranulation was assessed as release of elastase, measured with a specific substrate and as release of lactoferrin measured with ELISA. The neutrophils from the patients showed a significantly higher chemiluminescence and a slightly higher release of elastase, whereas the release of lactoferrin was the same in both groups. In contrast, the ratio between the 2 degranulation products, elastase and lactoferrin, was significantly higher in the group with periodontitis. A flow cytometric analysis of the membrane expression of the adhesion molecules CD 11a, CD 11b, CD 15, CD 16, CD 35 and Mel 14 showed no differences in the median immunofluorescence between the 2 groups. This study showed a more than 2-fold higher release of free oxygen radicals from Fc-gamma-receptor stimulated neutrophils compared with healthy controls, which indicates a specific neutrophil-associated host response in adult periodontitis.

Adult↗
PubMed1984

Decrease of Fc gamma and C3b receptor-bearing granulocytes and of T lymphocytes in myelomatosis.

18 patients with myelomatosis had lower percentages of granulocytes bearing receptors for Fc gamma (47.6%) and C3b (43.0%) than controls (80.4% and 75.0%). The percentage of T lymphocytes was decreased in patients when untreated sheep erythrocytes were used as indicator cells. Patients with high serum IgG levels had lower percentages of T lymphocytes. There was no significant difference in receptor profile between treated and untreated patients. The decrease in Fc gamma and C3b receptor-bearing granulocytes in myelomatosis is probably not due to serum or plasma factors since (a) the distribution of receptor-bearing lymphocytes was not different from that of the controls; (b) extra washings of cells or overnight incubation did not enhance the percentage of receptor positive cells; and (c) incubation of normal granulocytes in sera or plasma from myelomatosis patients did not cause a more pronounced reduction in the proportions of Fc gamma of C3b receptor-bearing cells than incubation in normal sera or plasma.

Aged↗
PubMed1993

Increased polymorphonuclear leukocyte Fc gamma-dependent chemiluminescence in active psoriasis is not related to FcRIII (CD16) receptor expression.

The role of the two main serum opsonins (IgG and C3b) in the induction of polymorphonuclear leukocyte chemiluminescence was studied in a group of psoriatic patients. Chemiluminescence was stimulated with zymosan opsonized by fresh plasma (IgG- and C3b-dependent chemiluminescence) or by complement-depleted plasma (IgG-dependent chemiluminescence). While C3b-dependent chemiluminescence was similar in patients with chronic or active forms of psoriasis, IgG-dependent chemiluminescence was significantly increased in patients with active disease. However, FcR-III expression, evaluated by means of flow cytofluorimetry, was similar in the different groups of patients studied. The discrepancy between Fc-receptor (CD16) expression and IgG-dependent chemiluminescence is, therefore, indicative of modifications that occur in psoriatic neutrophils that do not involve FcIII-receptor expression.

Adult↗
PubMed1999

Antigen activation of THP-1 human monocytic cells after stimulation with lipopolysaccharide from oral microorganisms and granulocyte-macrophage colony-stimulating factor.

A human THP-1 monocyte cell line culture system has been utilized to evaluate the morphological changes in THP-1 cells and to measure expression of activation antigens (CD-11b, CD-11c, CD-14, CD-35, CD-68, CD-71 and HLA-DR) as evidence of maturation of THP-1 cells in response to stimulation by lipopolysaccharide (LPS) from the oral microorganisms, Fusobacterium nucleatum and Porphyromonas gingivalis, and granulocyte-macrophage colony-stimulating factor. THP-1 cells were stimulated with LPS (1 microgram/ml) of P. gingivalis or F. nucleatum for different time periods (1, 2, 4 and 7 d). Detection of different activation antigens on THP-1 cells was performed by indirect immunohistochemical staining followed by light microscopy. Confirmational studies were performed in parallel using indirect immunofluorescence and immunogold electron microscopy for detection of the corresponding activation antigens. Expression of different activation antigens by resting THP-1 cells revealed HLA-DR to be on 3% of the cells; CD-11b, 9%; CD-11c, 8%; CD-14, 22%; CD-35, 9% and CD-68, 7%. The CD-71 activation antigen was not expressed in untreated THP-1 cells. LPS stimulation increased expression of all activation antigens. A significant (p < 0.05) increase in expression of CD-11b, CD-11c, CD-14, CD-35, CD-68 and CD-71 was observed when GM-CSF (50 IU/ml) was supplemented during the treatment of THP-1 cells with LPS of F. nucleatum or P. gingivalis. Activation and differentiation of THP-1 cells by LPS from oral microorganisms in the presence of GM-CSF supports a role for human macrophages in acute and chronic periodontal diseases and may explain the clinically observable periodontal exacerbations in some patients after GM-CSF therapy.

Antigens, CD↗
PubMed1991

Study on nonspecific immunity in pregnant women: II. Effect of hormones on chemiluminescence response of peripheral blood phagocytes.

To analyze the mechanisms of increased nonspecific immunity in pregnant women, the effect of various hormones on the phagocytic activity was estimated by a luminol-dependent chemiluminescence (CL) response during phagocytosing opsonized zymosan. The CL response of whole blood supplemented with exogenous human chorionic gonadotropin (hCG) increased significantly in all the male and female subjects and pregnant women. An approximate two- to fourfold increase was observed in comparison with the unsupplemented control in each subject at concentrations ranging from 1 to 1,000 IU/ml after 48 h of incubation (P less than 0.05). Progesterone slightly stimulated the CL response in female subjects only, but had no effect on male and pregnant women. Estradiol (E2) did not stimulate the CL response in any subject. The expression of Fc and C3b receptors on the surface of polymorphonuclear leucocytes (PMNL) in pregnant women was also investigated by measuring the immunofluorescence stained with monoclonal antibody to Fc and C3b receptors, respectively. The relative numbers of Fc receptors increased significantly in the third trimester compared to those of female control (P less than 0.05). Those of C3b receptor also increased in the second and third trimester (P less than 0.005). These results suggested that the nonspecific immunity represented by phagocytic activity in pregnant women increased with both oxidative metabolic responsiveness and the expression of membrane receptors. Besides, the increased phagocytic activity of the maternal host is probably due to the stimulatory effect of both endogenous and exogenous hCG on their peripheral blood phagocytes.

Adult↗
PubMed1992

Immunosuppression by human seminal plasma--extracellular organelles (prostasomes) modulate activity of phagocytic cells.

PROBLEM: Prostasomes are trilamellar to multilamellar vesicles produced by the acinar cells of the human prostate and are present in appreciable amounts in normal human semen. The aim of this work was to study the effect of prostasomes on human polymorphonuclear cell and monocyte function. METHODS: Functional activity of human neutrophils and monocytes was studied after incubation with prostasomes isolated from normal human seminal plasma. The following functional tests were employed: ability to ingest latex particles and opsonized bacteria (St. aureus) and ability to generate superoxide anion in response to PMA and FMLP. The latter was determined by measuring the superoxide-dismutase inhibitable reduction of ferricytochrome c to ferrocytochrome c at 550 nm. Expression of cell surface markers and interactions of prostasomes with cells were studied by cytofluorimetry. RESULTS: We show that prostasomes bind rapidly to the leukocyte cell membrane followed by internalization of adsorbed material. Interactions of prostasomes with neutrophils and monocytes inhibits their ability to phagocytose latex particles. The ability to ingest opsonized bacteria is, however, not impaired. Our results also show that incubation of leukocytes with prostasomes effectively inhibits superoxide anion generation in response to activation by PMA and FMLP. CONCLUSIONS: Prostasomes may play a complementary role to other immunosuppressive factors contained in the human semen. They may protect sperm cells from deleterious effects of phagocytosing cells, prolong their life, and consequently enhance the chance of conception. At the same time prostasomes may have a permissive effect on sexually transmitted diseases.

Cell Adhesion↗
PubMed1986

Granulocyte function in patients with multiple sclerosis.

Peripheral blood granulocytes and sera from patients with relapsing/remittent (group I) and chronic progressive (group II) multiple sclerosis (MS) did not differ from control cells and sera with regard to the proportion of cells bearing receptors for Fc gamma and C3b; random or directed (chemotactic) motility of granulocytes; activation as measured by chemiluminescence; opsonic activity of sera. The results of this study suggest that granulocyte function in MS is normal.

Cell Movement↗
PubMed1989

Different effects of ethanol on particle phagocytosis via different receptors in human monocytes.

Endocytosis of test particles by human blood monocytes (Mo) was tested in the presence of ethanol (80 mM). Phagocytosis via the Fc (IgG)- or C3b receptors (R) was assessed by an assay in which IgG- or C3b coated sheep erythrocytes (E) were used as test particles. Latex particles were tested in parallel with opsonized E. Phagocytosis of IgG-E was reduced to 67 +/- 5% of control (= without ethanol), while the corresponding value for C3b-E was 164 +/- 26% controls. Phagocytosis of latex particles was not affected by ethanol exposure (91 +/- 8% of control). The receptor functions were also tested without ethanol present during the assays. In this part of the study, Mo were incubated with or without ethanol in autologous serum for 15 min at 37 degrees C. After washing the cells free of ethanol, binding properties of the Fc-R or C3b-R were assessed by a rosette assay. Preincubation with ethanol reduced Fc-R binding, while attachment to C3b-R seemed to be more effective. The experiments thus indicate different effects of ethanol treatment in vitro on phagocytic receptors in human Mo. Control experiments revealed no direct effect of ethanol on the test particles.

Antigens, Differentiation↗
PubMed1999

Functional differentiation of acute myeloid leukaemia blast cells.

Little is known of the functional status of blast cells from patients with acute myeloid leukaemia (AML). We have studied phagocytosis and membrane receptors by flow cytometry (FCM), and secretory activities in blast cells from 24 AML patients prior to treatment. Blast cells from 11/16 patients attached N. meningitidis, and internalization occurred in 7/14. The phagocytosis of zymosan particles and N. meningitidis correlated linearly (r = 0.9, p<0.01, n = 11). Surface membrane expression of CD32 and CD11b was sufficient to account for opsonin-dependent attachment in all except one patient. A significant fraction of the blast cells attached, but did not internalize meningococci. CD32 and CD11b were non-functional in all the blasts from five patients, and in a subpopulation from seven additional patients. Significantly more large than small blasts expressed CD32, CD35 and CD11b (p<0.001). Phagocytosis was unrelated to the secretion of IL-1alpha, IL-1beta, and TNFalpha. In conclusion, AML blast cell function is related to receptor expression, cell size and granularity, and to FAB-type.

Adult↗
PubMed1983

Interaction of phagocytes with other blood cells and with pathogenic and nonpathogenic microbes.

Owing to the high surface tension of blood cells and to the equally high surface tension of their liquid habitat, the Hamaker coefficients A131 of blood cells (subscript 1) in blood (subscript 3), are unusually small; they are of the order of 0.25 to 2.5 X 10(-16) ergs. The very small van der Waals attractions such low Hamaker coefficients give rise to, coupled to the medium low but still sizable negative xi-potentials (-11 to -18 mV) of the cells, which cause an appreciable mutual electrostatic repulsion between blood cells, have been used to elaborate potential energy vs. distance diagrams, which closely reflect the unusual stability of blood cells in blood. When bacteria find their way into the bloodstream, they initially form an almost equally stable suspension. However, relatively hydrophobic nonpathogenic bacteria quickly aspecifically adsorb immunoglobulin G (IgG) molecules from blood serum, whilst hydrophilic pathogenic bacteria sooner or later also become coated with specific antibody molecules of the IgG-class. Through receptor sites on the surface of phagocytic blood cells, which can specifically bind to the Fc tails of IgG molecules, bacteria are first bound and then removed from the blood circulation and surrounding tissues. These Fc-receptor bonds presumably also are of a combined van der Waals and electrostatic nature. Thus in the normal course of events and by purely physicochemical mechanisms, phagocytic leukocytes will neither interfere with other leukocytes nor with any other blood cells, whilst they specifically interact with microorganisms and other unwanted foreign particles via IgG-IgG-receptor interactions. Also discussed, in the light of the principles elaborated above, are: some of the antiphagocytic mechanisms developed by certain pathogenic bacteria; the phagocytic disposal of aged, weak, or abnormal blood cells; and the role played by immunoglobulins other than IgG, and by complement, in the removal of bacteria and viruses.

Adhesiveness↗