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PubMed1987

Paroxysmal nocturnal hemoglobinuria: termination in acute monocytic leukemia and reappearance after chemotherapy with N4-palmitoyl-1-beta-D-arabinofuranosylcytosine (PL-AC) and vincristine.

Acute monocytic leukemia developed in a 77-year-old woman about 18 months after a diagnosis of paroxysmal nocturnal hemoglobinuria (PNH) had been made. The classical features of PNH disappeared with the onset of the leukemia. Chemotherapy with N4-palmitoyl-1-beta-D-arabinosylcytosine and vincristine resulted in the disappearance of leukemic cells in the bone marrow, during which time intravascular hemolysis recurred and the results of a Ham's test were again positive. The anemia and thrombocytopenia, however, were not improved. The present case report suggests the disappearance of the leukemic cells to imply not bone marrow remission but the return of PNH.

Aged↗
PubMed1977

Studies of antibody-dependent cytotoxicity in a plaque assay: evidence of human monocyte-like effector cells.

Two different methods for evaluating 'in vitro' cytotoxicity against antibody-coated target cells mediated by mononuclear leukocytes were compared. One was a plaque assay for identification of the cytotoxic cell and the other the classical chromium release assay for antibody-dependent cytotoxicity (ADCC). A marked decrease in plaque-forming cells (PFC) was observed in a cell suspension depleted of peroxidase-positive cells and cells with membrane-bound Ig (B lymphocytes) by fractionation on a nylon fiber column. In contrast, the ADCC activity was considerably increased by these depletions. A similar effect was obtained by removal of phagocytic cells with iron. These results, together with the observations after depletion of E-RFC (T lymphocytes) or EA-RFC (Fc-receptor-bearing cells), suggest that the PFC in the assay system used were of monocytic origin and differnet from the cells responsible for the ADCC.

Animals↗
PubMed1989

Plasmacytoid monocytes (so-called plasmacytoid T cells) in granulomatous lymphadenitis.

Immunohistochemical evidence that the plasmacytoid T cell is closely related to the blood monocyte has been reported, and the term plasmacytoid monocyte has been proposed to describe this cell. The present study was undertaken to analyze the presence and distribution of plasmacytoid monocytes in human reactive lymph nodes showing epithelioid cell reactions. Numerous plasmacytoid monocytes (detected by a panel of monoclonal antibodies) were found in the majority of the lymph nodes studies, usually in close topographical association with epithelioid cells and multinucleated giant cells. The present findings suggest that plasmacytoid monocytes may give rise to epithelioid cells. This is further supported by the ultrastructural similarities between plasmacytoid monocytes and plasmacytoid epithelioid cells, a cell type that has been identified previously in granulomas and considered a direct precursor of the classical epithelioid cell.

Granuloma↗
PubMed1987

Opioid-mediated suppression of interferon-gamma production by cultured peripheral blood mononuclear cells.

Mounting evidence suggests that opiate addiction and stress are associated with impaired cell-mediated immunity. We tested the hypothesis that morphine and the endogenous opioid beta-endorphin (beta-END), a pituitary peptide released in increased concentrations during stress, can suppress the production of the key macrophage-activating lymphokine interferon-gamma (IFN-gamma) by cultured human peripheral blood mononuclear cells (PBMNC). Using a radioimmunoassay to measure IFN-gamma, we found that exposure of PBMNC to biologically relevant concentrations of both opioids significantly inhibited IFN-gamma generation by cells stimulated with concanavalin A and varicella zoster virus. Studies of the mechanism of suppression revealed (a) a classical opioid receptor is involved (suppression was antagonized by naloxone and was specific for the NH2 terminus of beta-END), (b) monocytes are the primary target cell for opioids (monocyte-depleted lymphocyte preparations showed little suppression), and (c) reactive oxygen intermediates (ROI) and prostaglandin E2 are important mediators (scavengers of ROI and indomethacin eliminated the suppression). Based on these findings we suggest that opioid-triggered release of inhibitory monocyte metabolites may play a role in the immunodeficiency associated with narcotic addiction and stress.

Blood Cells↗
PubMed1989

A longitudinal study of the leukocyte protein L1 as an indicator of disease activity in patients with rheumatoid arthritis.

L1 is a major granulocyte and monocyte protein. It is released during leukocyte activation, and the plasma level is thought to reflect the inflammatory activity. Fifteen patients with classical or definite rheumatoid arthritis were examined monthly during one year. The laboratory tests included L1, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), orosomucoid, haptoglobin, ceruloplasmin, alpha 1-antitrypsin, immunoglobulins and blood cell counts. The clinical tests included articular index, grip strength, morning stiffness and pain. The L1 protein was found to have highly significant correlations (p less than 0.0001) with orosomucoid (r = 0.86), CRP (r = 0.79), ESR (r = 0.78), haptoglobin (r = 0.75), alpha 1-antitrypsin (r = 0.63) and ceruloplasmin (r = 0.44). Significant correlation was also found between L1 and IgA. None of the laboratory variables showed significant correlation with pain, but when they were correlated with articular index, grip strength and morning stiffness, L1 was found to have the highest average correlation coefficient (p less than 0.0001).

Adult↗
PubMed1989

The origin of the osteoclast.

The origin of the osteoclast remains controversial even though investigations using light microscopy, tissue culture, electron microscopy, microcinematography, autoradiography, parabiosis, quail chick nuclear markers, giant lysosomal markers in beige mice, Y chromosomes, bone marrow cell culture, and monoclonal antibodies have been performed since its discovery. Concepts of the origin of the osteoclast have been changing. The classic concept was that the osteoclast originated from connective tissue cells. Others hypothesized that it originated from mature hematopoietic cells, particularly from monocyte or macrophage cells. A recent concept proposed an origin from hematopoietic stem cells. The hematopoietic stem cell was believed to differentiate into two cell lineages: one of monocytes and the other of preosteoclasts. The authors' concept, based on experimental observations as well as alternate interpretations stemming from experimental reports of other researchers, proposes an origin from local, nonhematopoietic, possibly perivascular mesenchymal cells. However, the relationship of the hematopoietic stem cells to perivascular mesenchymal cells in the periosteum at an early stage of enchondral ossification is still not well known. Therefore, the origin of the osteoclast also remains uncertain.

Animals↗
PubMed1991

Cytomegalovirus preferentially infects a monocyte derived macrophage/microglial cell in human brain cultures: neuropathology differs between strains.

Cytomegalovirus (CMV) has been shown through pathologic examination to infect many cell types of the brain; however, neuropathology specific for CMV has been difficult to prove in the absence of classic cytomegalic cells or demonstration of CMV antigens. In an effort to further understand CMV infection of brain tissue, a human brain cell aggregate system was infected with several strains of CMV. Different neuropathologic changes were observed that were related to CMV strain and multiplicity of infection. These changes were consistent with those considered characteristic for human immunodeficiency virus (HIV) infection, including a nodular and multinucleated giant cell formation. By electron microscopy, only a few cells throughout the aggregates demonstrated intranuclear virions. These cells were identified by ultrastructural morphology as either monocyte derived macrophages or microglial cells (M/M). Antigen expression was observed in these cells with and without neuropathologic changes. Infection progressed in either a diffuse fulminant manner or a more focal cell to cell spread. These studies demonstrate that CMV selectively infects M/M in normal human brain cultures and suggests differences in neuropathology based on multiplicity of infection and strain variation.

Brain↗
PubMed1984

Effect of the caprine variant of Mycoplasma mycoides subsp mycoides on endothelium, monocytes, and complement of guinea pig, calf, sheep, and goat serum.

The caprine variant of Mycoplasma mycoides subsp mycoides causes septicemia with coagulopathy in goats. Pathogenetic mechanisms that might explain the coagulopathy, the ability of the Mycoplasma to persist in the blood, and its specificity for goats were studied. Severe endothelial damage was seen by electron microscopy of goat aorta tissue exposed in vitro to 10(7) colony-forming units of mycoplasmas. The Mycoplasma did not damage 51Cr-labeled adherent cells from peripheral blood of goats. The hemolytic complement titer was reduced by 94%, 50%, 50%, and 25% in guinea pig, calf, sheep, and goat serum, respectively, 30 minutes after treatment with 8 X 10(9) colony-forming units of the Mycoplasma. Freshly prepared serum from these animal species killed the Mycoplasma. Heat-inactivated serum was not mycoplasmacidal. Complement from these 4 animal species was activated by the Mycoplasma through the classical pathway, because ethyleneglycoltetraacetic acid precipitation of serum Ca2+ inhibited activation. Proof that the classical pathway was functional in goats was not conclusive because Ca2+ supplementation of ethyleneglycoltetraacetic acid-treated serum did not restore complement activity. Endothelial damage and complement activation may explain the coagulopathy. The function that complement activation may have in the inflammatory response of this disease is not known. Difference in susceptibility of calves, sheep, and goats to M mycoides septicemia cannot be explained by species variation in complement mycoplasmacidal activity.

Animals↗
PubMed2000

Thioredoxin reductase, a redox-active selenoprotein, is secreted by normal and neoplastic cells: presence in human plasma.

Thioredoxin (Trx) and Trx reductase (TrxR) are redox-active proteins that participate in multiple cellular events, including growth promotion, apoptosis, and cytoprotection. Studies on overexpression of Trx and TrxR in human cancers have indicated a role of these proteins in tumor development. In this study, we analyzed the expression of TrxR in peripheral blood cells, tumor-transformed leukemia, and melanoma cells and found, in addition to abundant plasma membrane localization, that TrxR was released from these cells. Secretory cells were observed at the single cell level using a sensitive enzyme-linked immunospot assay. The release was inducible, and physiological stimulation of human monocytes by IFN-gamma, lipopolysaccharide, and interleukin 1alpha significantly increased the number of TrxR-secreting cells (P = 0.004). Secretion of TrxR followed the classical Golgi pathway, and it was confirmed by metabolic labeling using [35S]methionine and [35S]cysteine. TrxR was also detected for the first time in fresh healthy blood donor plasma (n = 21; median concentration, 18.0 ng/ml), with biological activity as determined by insulin reduction assay. These results highlight the role of extracellular Trx and TrxR during inflammation and tumor progression. Released Trx, with its active site motif containing amino acids Cys-X-X-Cys, was recently shown to have chemoattractant properties beside its previously described antioxidant and cocytokine activities. Regeneration of oxidized Trx requires available TrxR outside the cell, the presence and induction of which is described in this paper for normal and transformed cells.

Amino Acid Motifs↗
PubMed2006

Wnt signaling regulates transendothelial migration of monocytes.

The Wnt-signaling pathway plays a critical role in directing cell fate during embryogenesis. Several lines of evidence also suggest a role in inflammatory processes. Here, we analyzed whether Wnt signaling plays a role in leukocyte inflammatory responses. Monocytes from healthy donors expressed different Frizzled receptors, which are ligands for the Wnt molecules. Activation of the Wnt/beta-catenin pathway by LiCl or Wnt3a increased beta-catenin protein levels in monocytes but not in granulocytes. It is interesting that the activation of Wnt/beta-catenin signaling via Wnt3a in monocytes resulted in a decrease in migration through an endothelial layer (human dermal microvascular endothelial cell-1). Further experiments revealed that the decrease in transendothelial migration was associated with specific monocyte adherence to endothelial cells after Wnt exposure. The specificity was verified by a lack of Wnt3a-induced adhesion to fibronectin, laminin, or collagen compared with endothelial interaction. Analysis of the distribution of beta-catenin revealed a Wnt3a-induced increase of beta-catenin in the cytoplasm. Wnt3a exposure did not result in any activation of the classical Wnt-target gene c-myc or a Wnt-target gene involved in cell adhesion (Connexin43). Our study implicates for the first time a role of canonical Wnt signaling in inflammatory processes in monocytes.

Animals↗
PubMed1992

Cloning and expression of a cDNA encoding a non-classical MHC class I antigen (HLA-E) in eosinophils from hypereosinophilic patients.

A cDNA library, constructed from purified blood eosinophils, was screened with the B cell CD23 cDNA probe. A clone designated EO15 has been isolated and found to encode a non-classical HLA class I gene transcript. EO15 was compared with HLA-E and found to be 99.9% similar at the nucleotide level and to extend further in the 3' untranslated region. The presence of an additional polyadenylation signal in the EO15 3' end suggests that EO15 clone represents a copy of the 3.3-kb mRNA species detected in Northern blot analyses. HLA-E transcripts of 1.9 and 3.3 kb have been described in a variety of cell types. The two EO15 mRNA species, similar in size to the previously defined HLA-E mRNA, were present at high levels in blood leukocyte populations and at variable levels in different cell lines. The EO15 transcripts were found at abundant levels in hypodense and normodense eosinophils from hypereosinophilic patients. In situ hybridization confirmed the expression of EO15 mRNA in eosinophils. Neutrophils and lymphocytes from normal donors of from patients with hypereosinophilia also strongly expressed EO15 mRNA. Among the cell lines studied, the highest levels of EO15 transcripts were detected in B and monocytic cell lines, whereas intermediate and lower levels were found in eosinophilic, NK-like, megakaryocytic, and T cell lines, respectively. Similar to its effect on classical HLA class I transcripts, IFN-gamma increased the levels of EO15 mRNA in eosinophils and neutrophils from hypereosinophilic patients. These results suggest that purified blood eosinophils as well as neutrophils express EO15/HLA-E mRNA; however, further experiments are needed to investigate the localization and the function of EO15 protein products.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1999

ATP-binding cassette transporter A1 (ABCA1) in macrophages: a dual function in inflammation and lipid metabolism?

Activated lipid-laden macrophages in the vascular wall are key modulators of the inflammatory processes underlying atherosclerosis. We demonstrate here that the ATP-binding cassette (ABC) transporter ABCA1 is induced during differentiation of human monocytes into macrophages. ABCA1 has been implicated in macrophage interleukin-1beta secretion and apoptosis. Moreover, ABCA1 mRNA and protein levels are strongly upregulated by uptake of modified LDL and downregulated by HDL(3)-mediated lipid efflux in macrophages. Mutation analysis in patients with the classical Tangier disease (TD), a monogenetic disorder characterized by hypersplenism, macrophage accumulation and deposition of cholesteryl esters in the reticuloendothelial system, low plasma HDL and premature atherosclerosis, revealed deleterious mutations in their ABCA1 gene. The localization pattern of the mutations within the ABCA1 protein appears to determine the tropism for either the reticuloendothelial system, as seen in the classical TD phenotype, or the artery wall, as in the case of HDL deficiency in the absence of splenomegaly. In a comprehensive analysis of the expression and regulation of all currently known human ABC transporters, we identified additional cholesterol-responsive genes that are induced during monocyte differentiation into macrophages. Our results indicate a dual regulatory function for ABCA1 in macrophage lipid metabolism and inflammation.

ATP Binding Cassette Transporter 1↗
PubMed2006

Protein kinase C beta and delta isoenzymes mediate cholesterol accumulation in PMA-activated macrophages.

Previously, we showed that PMA activation of human monocyte-derived macrophages stimulates macropinocytosis (i.e., fluid-phase endocytosis) of LDL and transforms these macrophages into foam cells. The current study aimed to learn which PKC isoenzymes mediate cholesterol accumulation in PMA-activated human macrophages incubated with LDL. Cholesterol accumulation by PMA-activated macrophages incubated with LDL was nearly completely inhibited (>85%) by the pan PKC inhibitors Go6850, Go6983, and RO 32-0432, but only was inhibited about 50% by the classical group PKC inhibitor, Go6976. This indicated that cholesterol accumulation was mediated by both a classical group and some other PKC isoenzyme. PKC beta was determined to be the classical group isoenzyme that mediated PMA-stimulated cholesterol accumulation. A pseudosubstrate myristoylated peptide inhibitor of PKC alpha and beta showed partial inhibition (congruent with 50%) of cholesterol accumulation. However, a small molecule inhibitor of PKC alpha, HBDDE, show minimal inhibition of cholesterol accumulation while a small molecule inhibitor of PKC beta, LY333513, could completely account for the inhibition of cholesterol accumulation by the classical group PKC isoenzyme. Thus, our findings show that beta and some other PKC isoenzyme, most likely delta, mediate cholesterol accumulation when macropinocytosis of LDL is stimulated in PMA-activated human monocyte-derived macrophages.

Atherosclerosis↗
PubMed2004

Th2 response of human peripheral monocytes involves isoform-specific induction of monoamine oxidase-A.

Monocyte/macrophage function is critically regulated by specific cytokines and growth factors that they are exposed to at inflammatory sites. IL-4 and IL-13 are multifunctional cytokines generated mainly by Th2 lymphocytes that have important biological activities in allergy and inflammation. The Th2 response of human peripheral monocytes is characterized by complex alterations in the gene expression pattern, which involves dominant expression of CD23 cell surface Ag and lipid-peroxidizing 15-lipoxygenase-1 (15-LOX1). In this study, we report that the classical Th2 cytokines IL-4 and IL-13 strongly up-regulate expression of monoamine oxidase A (MAO-A) with no induction of the closely related isozyme, MAO-B. Real-time PCR indicated a >2000-fold up-regulation of the MAO-A transcripts, and immunohistochemistry revealed coexpression of the enzyme with 15-LOX1 in a major subpopulation of monocytes. MAO-A was also induced in lung carcinoma A549 cells by IL-4 in parallel with 15-LOX1. In promyelomonocytic U937 cells, which neither express 15-LOX1 nor MAO-A in response to IL-4 stimulation, expression of MAO-A was up-regulated following transfection with 15-LOX1. This is the first report indicating expression of MAO-A in human monocytes. Its isoform-specific up-regulation in response to Th2 cytokines suggests involvement of the enzyme in modulation of innate and/or acquired immune system.

Arachidonate 15-Lipoxygenase↗
PubMed2006

Kaposi's sarcoma-associated herpesvirus viremia is associated with the progression of classic and endemic Kaposi's sarcoma.

In order to gain further insight on the role of Kaposi's sarcoma-associated herpesvirus (KSHV) in classic and endemic Kaposi's sarcoma (KS) pathogenesis, we aimed to determine (i) whether KSHV is detectable in peripheral blood mononuclear cells (PBMCs), (ii) which PBMCs subpopulation harbor the virus, (iii) which clinical, histologic, and immunologic parameters are associated with KSHV viremia in a population of classic and endemic KS. KSHV viremia and various immunologic parameters were screened on 81 patients. KSHV viremia was positive in 58% of the patients. KSHV was detected in B cells, T cells, and monocytes. CD34+ cells depleted in circulating endothelial cells (CECs) were never infected and 50% of the patients tested had CECs infected by KSHV. We observed a significant increase of IL-2 and IFN-gamma production by CD4 T cells and an increase of IFN-gamma production by CD8 T cells compared to control patients. KS progression (P = 0.001) and KS staging (P = 0.03) were significantly and independently associated with positive KSHV viremia. Our results show that there is no specific immunosuppression in classic or endemic KS. We showed that KSHV can be detected within CECs and that KSHV viremia could be an indicator of circulating mature or precursor spindle cells.

Aged↗
PubMed2003

Immunomodulatory activity and chemical characterisation of sangre de drago (dragon's blood) from Croton lechleri.

The immunomodulatory activity of the latex from Croton lechleri (sangre de drago) was determined by in vitro assays. Classical (CP) and alternative (AP) complement pathways activities were determined in human serum. Intracellular generation of reactive oxygen species (ROS) by human polymorphonuclear leukocytes (PMNs) and monocytes, and phagocytosis of opsonised fluorescent microspheres were measured by flow cytometry. Free radical scavenging activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Activity on proliferation of murine lymphocytes was also investigated. In addition, anti-inflammatory activity was assayed in vivo by carrageenan-induced rat paw oedema test. Some of the activities were compared with those of the isolated alkaloid taspine. Sangre de drago from Croton lechleri showed immunomodulatory activity. It exhibited a potent inhibitory activity on CP and AP of complement system and inhibited the proliferation of activated T-cells. The latex showed free radical scavenging capacity. Depending on the concentration, it showed antioxidant or prooxidant properties, and stimulated or inhibited the phagocytosis. Moreover, the latex has strong anti-inflammatory activity when administered i. p. Taspine cannot be considered the main responsible for these activities, and other constituents, probably proanthocyanidins, should be also involved.

Adjuvants, Immunologic↗