scholarly journals Activated human monocytes inhibit the intracellular multiplication of legionnaires' disease bacteria

1981 ◽  
Vol 154 (5) ◽  
pp. 1618-1635 ◽  
Author(s):  
MA Horwitz ◽  
SC Silverstein
Keyword(s):  
Mononuclear Cell ◽  
Cell Cultures ◽  
Present Report ◽  
Human Lymphocytes ◽  
Cell Mediated Immunity ◽  
Human Monocytes ◽  
Con A ◽  
Legionnaires Disease ◽  
Intracellular Multiplication ◽  
Activated Monocytes

We have examined the interaction between virulent egg yolk-grown L. pneumophila, Philadelphia 1 strain, and in vitro-activated human monocytes, under antibiotic-free conditions. Freshly explanted human monocytes activated by incubation with concanavalin A (Con A) and human lymphocytes inhibited the intracellular multiplication of L. pneumophila. Both Con A and lymphocytes were required for activation. Con A was consistently maximally effective at greater than or equal to 4 μg/ml. Monocytes activated by incubation with cell-free filtered supernatant from Con A-sensitized mononuclear cell cultures also inhibited the intracellular multiplication of L. pneumophil a. The most potent supernatant was obtained from mononuclear cell cultures incubated with greater than or equal to 15 μg/ml Con A for 48 h. The degree of monocyte inhibition of L. pneumophila multiplication was proportional to the length of time monocytes were preincubated with supernatant (48 {greater than} 24 {greater than} 12 h) and to the concentration of supernatant added (40 percent {greater than} 20 percent {greater than} 10 percent {greater than} 5 percent). Monocytes treated with supernatant daily were more inhibitory than monocytes treated initially only. With time in culture, monocytes progressively lost a limited degree of spontaneous inhibitory capacity and also lost their capacity to respond to supernatant with inhibition of L. pneumophila multiplication. Supernatant-activated monocytes inhibited L. pneumophila multiplication in two ways. They phagocytosed fewer bacteria, and they slowed the rate of intracellular multiplication of bacteria that were internalized. As was the case with nonactivated monocytes, antibody had no effect on the rate of intracellular multiplication in supernatant-activated monocytes. Neither supernatant-activated nor nonactivated monocytes killed L. pneumophila in the absence of antibody. Both killed a limited proportion of these bacteria in the presence of antibody and complement. We have previously reported that anti-L, pneumophila antibody and complement neither promote effective killing of L. pneumophila by human polymorphonuclear leukocytes and monocytes nor inhibit the rate of L. pneumophila multiplication in monocytes. These findings and our present report that activated monocytes do inhibit L. pneumophila multiplication indicate that cell-mediated immunity plays a major role in host defense against Legionnaires' disease.

scholarly journals Legionella pneumophila inhibits acidification of its phagosome in human monocytes.

1984 ◽  
Vol 99 (6) ◽  
pp. 1936-1943 ◽  
Author(s):  
M A Horwitz ◽  
F R Maxfield
Keyword(s):  
Legionella Pneumophila ◽  
Sheep Erythrocyte ◽  
Bacterial Pathogen ◽  
Human Monocytes ◽  
E Coli ◽  
The Mean ◽  
Intracellular Multiplication ◽  
Fluorescence Images ◽  
Activated Monocytes ◽  
Quantitative Fluorescence

We used quantitative fluorescence microscopy to measure the pH of phagosomes in human monocytes that contain virulent Legionella pneumophila, a bacterial pathogen that multiplies intracellularly in these phagocytes. The mean pH of phagosomes that contain live L. pneumophila was 6.1 in 14 experiments. In the same experiments, the mean pH of phagosomes containing dead L. pneumophila averaged 0.8 pH units lower than the mean pH of phagosomes containing live L. pneumophila, a difference that was highly significant (P less than 0.01 in all 14 experiments). In contrast, the mean pH of phagosomes initially containing live E. coli, which were then killed by monocytes, was the same as for phagosomes initially containing dead E. coli. The mean pH of L. pneumophila phagosomes in activated monocytes, which inhibit L. pneumophila intracellular multiplication, was the same as in nonactivated monocytes. To simultaneously measure the pH of different phagosomes within the same monocyte, we digitized and analyzed fluorescence images of monocytes that contained both live L. pneumophila and sheep erythrocytes. Within the same monocyte, live L. pneumophila phagosomes had a pH of approximately 6.1 and sheep erythrocyte phagosomes had a pH of approximately 5.0 or below. This study demonstrates that L. pneumophila is capable of modifying the pH of its phagocytic vacuole. This capability may be critical to the intracellular survival and multiplication of this and other intracellular pathogens.

scholarly journals Formation of a novel phagosome by the Legionnaires' disease bacterium (Legionella pneumophila) in human monocytes.

1983 ◽  
Vol 158 (4) ◽  
pp. 1319-1331 ◽  
Author(s):  
M A Horwitz
Keyword(s):  
Legionella Pneumophila ◽  
Vacuolar Membrane ◽  
Common Mechanism ◽  
Cytoplasmic Vacuole ◽  
Human Monocytes ◽  
Vacuole Formation ◽  
Cytoplasmic Organelles ◽  
Membrane Bound ◽  
Legionnaires Disease ◽  
Intracellular Multiplication

Previous studies have shown that L. pneumophila multiplies intracellularly in human monocytes and alveolar macrophages within a membrane-bound cytoplasmic vacuole studded with ribosomes. In this paper, the formation of this novel vacuole is examined. After entry into monocytes, L. pneumophila resides in a membrane-bound vacuole. During the first hour after entry, vacuoles containing L. pneumophila are found surrounded by smooth vesicles fusing with or budding off from the vacuolar membrane and by mitochondria closely apposed to the vacuolar membrane. By 4 h, vacuoles are found less frequently surrounded by these cytoplasmic organelles, but now ribosomes and rough vesicles are found gathered about the vacuole. By 8 h, the ribosome-lined vacuole has formed. Erythromycin, at concentrations that completely inhibit the intracellular multiplication of L. pneumophila, has no effect on vacuole formation. Formalin-killed L. pneumophila also reside in a membrane-bound vacuole after entry into monocytes. In contrast to the situation with live L. pneumophila, cytoplasmic organelles are not found surrounding vacuoles containing formalin-killed L. pneumophila at any time after entry. Formalin-killed bacteria are rapidly digested, and by 4 h, few remain intact. The L. pneumophila-containing vacuole has certain features in common with other intracellular organisms that inhibit phagosome-lysosome fusion; these organisms may share a common mechanism for vacuole formation and inhibition of phagosome-lysosome fusion.

Distribution of VLA-5 and VLA-4 fibronectin receptors in human monocytes demonstrated by immunofluorescence, immunocytochemistry, and autoradiography

1993 ◽  
Vol 51 ◽  
pp. 306-307
Author(s):  
Robert Williams ◽  
Che-Hung Lee ◽  
Sara E. Quella ◽  
David M. Harlan ◽  
Yuan-Hsu Kang
Keyword(s):  
Present Report ◽  
Matrix Proteins ◽  
Extracellular Matrices ◽  
Human Monocytes ◽  
Integrin Receptors ◽  
Morphological Evaluation ◽  
The Matrix ◽  
Specific Receptors ◽  
Cytokine Stimulation ◽  
Monocyte Adherence

Monocyte adherence to endothelial or extracellular matrices plays an important role in triggering monocyte activation in extravascular sites of infection, chronic inflammatory disorders, and tissue damage. Migration of monocytes in the tissues involves the response to a chemoattractant and movement by a series of attachments and detachments to the extracellular matrices which are regulated by expression and distribution of specific receptors for the matrix proteins such as fibronectin (FN). The VSAs (very late antigens or beta integrins), a subfamily of the transmembrane heterodimeric integrin receptors, have been thought to play a major role in monocyte adherence to the extracellular matrices and cells. In this subfamily, VLA-5 and VLA-4 are believed to be the most essential integrins mediating monocyte adherence to FN. In the present report, we have established and compared different procedures for morphological evaluation of the expression and distribution of the FN receptors on human monocytes in order to investigate their response to endotoxin or cytokine stimulation.

Depressed Blastic Development of Human Lymphocytes in PHA-Cell-Cultures after Intravenous Injection of PHA

1967 ◽  
Vol 31 (6) ◽  
pp. 568-574 ◽  
Author(s):  
G. Astaldi ◽  
R. Airò ◽  
E. Rodriguez-Paradisi ◽  
E. Novelli ◽  
T. Lisino
Keyword(s):  
Intravenous Injection ◽  
Cell Cultures ◽  
Human Lymphocytes

Distinct Neopterin Excretion Patterns after Vaccination

Pteridines ◽  
1990 ◽  
Vol 2 (3) ◽  
pp. 147-149 ◽  
Author(s):  
Dietmar Fuchs ◽  
Arno Hausen ◽  
Gilbert Reibnegger ◽  
Ernst R. Werner ◽  
Gabriele Werner-Felmayer ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cellular Immunity ◽  
Tetanus Toxoid ◽  
Cell Activation ◽  
Cell Mediated Immunity ◽  
Soluble Antigen ◽  
Human Monocytes ◽  
Mumps Vaccine ◽  
Urinary Neopterin

Summary To compare the involvement of cellular immunity in response to vaccination we have investigated urinary neopterin levels in daily follow-ups of children after vaccination with live measles/mumps vaccine and of adults after boosting with the soluble antigen tetanus toxoid. Neopterin levels distinctly peaked 8 - 11 days after vaccination with measles/mumps vaccine. In contrast, after boosting with soluble antigen tetanus toxoid neopterin levels remained unaffected. Large amounts of neopterin are produced by human monocytes/ macro phages on stimulation with gamma interferon. In patients neopterin concentrations reflect activation of cell mediated immunity. The data imply that distinct pathways of T cell activation are triggered in humans after immunization with live vaccine and with soluble antigen .

scholarly journals Expression of the macrophage-specific colony-stimulating factor in human monocytes treated with granulocyte-macrophage colony-stimulating factor

Blood ◽  
1987 ◽  
Vol 69 (4) ◽  
pp. 1259-1261
Author(s):  
J Horiguchi ◽  
MK Warren ◽  
D Kufe
Keyword(s):  
T Cells ◽  
Gene Product ◽  
Phorbol Ester ◽  
Human Monocytes ◽  
Colony Stimulating Factor ◽  
Gm Csf ◽  
Macrophage Colony Stimulating Factor ◽  
Activated Monocytes ◽  
Macrophage Colony ◽  
Stimulating Factor

The macrophage-specific colony-stimulating factor (CSF-1, M-CSF) regulates the survival, growth and differentiation of monocytes. We have recently demonstrated that phorbol ester induces expression of CSF- 1 in human monocytes. These findings suggested that activated monocytes are capable of producing their own lineage-specific CSF. The present studies demonstrate that the granulocyte-macrophage colony-stimulating factor (GM-CSF) also induces CSF-1 transcripts in monocytes. Furthermore, we demonstrate that the detection of CSF-1 RNA in GM-CSF- treated monocytes is associated with synthesis of the CSF-1 gene product. The results thus suggest that GM-CSF may indirectly control specific monocyte functions through the regulation of CSF-1 production. These findings indicate another level of interaction between T cells and monocytes.

Dexamethasone-Induced Apoptosis of Human Monocytes Exposed to Immune Complexes. Intervention of CD95-and Xiap-Dependent Pathways

2005 ◽  
Vol 18 (3) ◽  
pp. 403-415 ◽  
Author(s):  
L. Ottonello ◽  
M. Bertolotto ◽  
F. Montecucco ◽  
P. Dapino ◽  
F. Dallegri
Keyword(s):  
Immune Complex ◽  
Immune Complexes ◽  
Therapeutic Option ◽  
Mek Inhibitor ◽  
Dependent Manner ◽  
Human Monocytes ◽  
Inflammatory Reactions ◽  
Activated Monocytes ◽  
Induced Apoptosis ◽  
Dose Dependent

Monocytes and macrophages play a key role in the initiation and persistence of inflammatory reactions. The possibility to interfere with the survival of these cells, once recruited and activated at sites of inflammation, is an attractive therapeutic option. Although resting monocytes are susceptible to pharmacologically induced apoptosis, no data are available about the possibility to modulate the survival of activated monocytes. The present work was planned to investigate if dexamethasone is able to promote apoptosis of human monocytes activated by immune complexes. When monocytes were cultured with immune complexes, a dose-dependent inhibition of apoptosis was observed. Dexamethasone stimulated apoptosis of resting and activated monocytes in a dose-dependent manner. Both the immune complex inhibitory activity and dexamethasone stimulatory properties depend on NF-kB/XIAP and Ras/MEK/ERK/CD95 pathways. In fact, the exposure of monocytes to immune complexes increased NF-kB activation and XIAP expression, which in turn were inhibited by dexamethasone. On the other hand, immune complex-stimulated monocytes displayed a reduced expression of CD95, which is prevented by dexamethasone, as well as by MEK inhibitor U0126. Furthermore, anti-CD95 ZB4 mAb prevented dexamethasone-induced apoptosis in immune complex-stimulated monocytes. Similarly, ZB4 inhibited dexamethasone-mediated augmentation of caspase 3 activity. The present findings suggest that Fc triggering by insoluble immune complexes result in the activation of two intracellular pathways crucial for the survival of monocytes: 1. Ras/MEK/ERK pathway responsible for the down-regulation of CD95 expression; 2. NF-kB pathway governing the expression of XIAP. Both the pathways are susceptible to inhibition by monocyte treatment with pharmacologic concentrations of dexamethasone.

scholarly journals A longitudinal immunologic evaluation of hemophiliac patients

Blood ◽  
1985 ◽  
Vol 66 (4) ◽  
pp. 993-998 ◽  
Author(s):  
RD deShazo ◽  
CB Daul ◽  
WA Andes ◽  
BE Bozelka
Keyword(s):  
Mononuclear Cell ◽  
Cell Function ◽  
Killer Cell ◽  
Cell Activity ◽  
Suppressor Cell ◽  
Cell Mediated Immunity ◽  
Biologic Response ◽  
Life Threatening ◽  
Generalized Lymphadenopathy ◽  
One Year

Abstract Over an average span of one year, we performed a prospective clinical and immunologic evaluation of 30 patients with hemophilia. No patient developed life-threatening opportunistic infection or malignancy; however, the immunologic abnormalities and lymphadenopathy initially present in nine patients (lymphadenopathy group) persisted. In addition, five patients, representing 24% of the initial group without lymphadenopathy, developed generalized lymphadenopathy (converter group). One episode of idiopathic thrombocytopenia (ITP) and one episode of staphylococcal sepsis occurred in this “converter” group; one episode of ITP also occurred in the lymphadenopathy group. Sixteen patients remained asymptomatic. At the time of the follow-up evaluation, those differences in mononuclear cell (MNC) percentages and numbers noted initially among the three hemophiliac groups were no longer present. Natural killer cell function alone or in the presence of biologic response modifiers was not different among hemophiliac and control groups. Before developing lymphadenopathy, the converter group of patients had significantly better lymphocyte mitogenic function than did the other two groups of patients with hemophilia. However, lymphocyte mitogenic responses of all groups of patients with hemophilia significantly deteriorated over the course of the study. The abnormal mitogenic responses noted in these patients was explained in part by higher levels of spontaneous suppressor cell activity in mononuclear cell preparations from patients with hemophilia. We conclude that long-term immunologic studies of this patient population requires both quantitative and qualitative evaluations. Our data show that patients with hemophilia have progressive dysfunction of cell- mediated immunity.

Sign in / Sign up

Export Citation Format

Share Document