Lower Monocyte Research Articles

Monocyte interleukin-12 production is inversely related to duration of respiratory failure in respiratory syncytial virus bronchiolitis.

The correlation of clinical and immunological parameters with the duration of respiratory failure was investigated to identify factors determining the clinical outcome of respiratory syncytial virus (RSV) bronchiolitis necessitating mechanical ventilation. At initiation of mechanical ventilation in 30 patients with RSV, production of interleukin (IL)-12 and IL-10 was measured in 48-h peripheral blood cell cultures that were stimulated with lipopolysaccharide and interferon-gamma. The ventilation index (VI)-an indicator of respiratory dysfunction that includes partial pressure of arterial CO2, peak airway pressure, and respiratory rate-correlated with the duration of mechanical ventilation (r=.47; P=.013). Age was not associated with the duration of mechanical ventilation. A highly significant inverse correlation was found between the duration of mechanical ventilation and the production of IL-12 at admission (r=-.62; P<.001). This correlation was independent of VI. No correlation was found between IL-10 production and the duration of mechanical ventilation. It is hypothesized that low monocyte IL-12 response during initial RSV infection adversely affects clinical outcome of patients with severe RSV bronchiolitis.

Regulation of low shear flow-induced HAEC VCAM-1 expression and monocyte adhesion.

We recently reported that prolonged exposure of human aortic endothelial cells (HAEC) to low shear stress flow patterns is associated with a sustained increase in the activated form of the transcriptional regulator nuclear factor-kappaB (NF-kappaB). Here we investigate the hypothesis that low shear-induced activation of NF-kappaB is responsible for enhanced expression of vascular cell adhesion molecule (VCAM-1) resulting in augmented endothelial cell-monocyte (EC-Mn) adhesion and that this activation is dependent on intracellular oxidant activity. Before exposure to low shear (2 dyn/cm2) for 6 h, HAEC were preincubated with or without the antioxidants pyrrolidine dithiocarbamate (PDTC) or N-acetyl-L-cysteine (NAC). PDTC strongly inhibited low shear-induced activation of NF-kappaB, expression of VCAM-1, and EC-Mn adhesion. Paradoxically, NAC exerted a positive effect on low shear-induced VCAM-1 expression and EC-Mn adhesion and only slightly downregulated NF-kappaB activation. However, cytokine-induced NF-kappaB activation and VCAM-1 expression are blocked by both PDTC and NAC. These data suggest that NF-kappaB plays a key role in low shear-induced VCAM-1 expression and that pathways mediating low shear- and cytokine-induced EC-Mn adhesion may be differentially regulated.

Monocyte Activation in Platelet Concentrates

Background and Objectives: Cytokines in platelet concentrates contribute to febrile transfusion reactions. Activated monocytes are a major source of inflammatory cytokines, however the role of monocytes in cytokine production in platelet concentrates has not been clarified. This study undertook to quantitate monocytes, determine whether monocyte activation occurs and identify an association with IL-6 and IL-1β concentrations in platelet concentrates. Materials and Methods: 17 platelet concentrates were analysed for total leucocyte and monocyte counts, CD14 and CD16 monocyte-associated antigen expression and IL-1β and IL-6 measurements on days 1, 2, 3, 4 and 5. Results: Monocytes in all platelet concentrates expressed increased levels of CD14 and CD16 from day 1 of storage. 10/17 platelet concentrates had elevated IL-6 levels by day 3. Platelet concentrates with IL-6 levels above 15 pg/ml on day 5 had monocyte counts between 0.14 and 15.6 × 10⁶/unit on day 1, while those with IL-6 levels below 15 pg/ml had low monocyte counts of < 0.01 to 1.2 × 10⁶/unit on day 1. Conclusion: Monocytes present in platelet concentrates exhibit features of activation. Monocyte activation is present following the preparation of platelet concentrates, implicating the manufacturing process in its development. Increased IL-6 and IL-1β levels during platelet concentrate storage are commonly associated with a higher monocyte count. However, no direct association could be identified between the extent of monocyte activation and the level of cytokine release.

Monocyte Activation in Platelet Concentrates

Abstract Background and Objectives: Cytokines in platelet concentrates contribute to febrile transfusion reactions. Activated monocytes are a major source of inflammatory cytokines, however the role of monocytes in cytokine production in platelet concentrates has not been clarified. This study undertook to quantitate monocytes, determine whether monocyte activation occurs and identify an association with IL‐6 and IL‐β concentrations in platelet concentrates. Materials and Methods: 17 platelet concentrates were analysed for total leucocyte and monocyte counts, CD14 and CD16 monocyte‐associated antigen expression and IL‐1β and IL‐6 measurements on days 1, 2, 3, 4 and 5. Results: Monocytes in all platelet concentrates expressed increased levels of CD14 and CD16 from day 1 of storage. 10/17 platelet concentrates had elevated IL‐6 levels by day 3. Platelet concentrates with IL‐6 levels above 15 pg/ml on day 5 had monocyte counts between 0.14 and 15.6×106/unit on day 1, while those with IL‐6 levels below 15 pg/ml had low monocyte counts of &lt;0.01 to 1.2×106/unit on day 1. Conclusion: Monocytes present in platelet concentrates exhibit features of activation. Monocyte activation is present following the preparation of platelet concentrates, implicating the manufacturing process in its development. Increased IL‐6 and IL‐1β levels during platelet concentrate storage are commonly associated with a higher monocyte count. However, no direct association could be identified between the extent of monocyte activation and the level of cytokine release.

Low density blood granulocytic cells induced during classical swine fever are targets for virus infection

Classical swine fever virus infection of pigs causes a severe leukopenia and immunosuppression. In the present study, the kinetics of virus infection, and identification of target cells for the virus in peripheral blood were analysed. Virus infection was often not detectable before 5–7 days p.i. A minority of animals yielded detectable infected cells at 3 days p.i., but <5% PBMC. It was not until 10 days p.i. that this figure increased-to 35–70% PBMC depending on the animal. Detailed analysis of Ficoll–Hypaque-purified PBMC identified the major population to be SWC3 +SWC8 +CD14 +MHCII − granulocytic cells. Microscopic observations determined that these low density granulocytic cells in the PBMC from CSFV infected animals were indeed immature cells. Both the low density granulocytic cells and monocytes were major targets for CSFV infection in the peripheral blood. This is the first demonstration that low density granulocytic cells dominate the blood leukocyte population during CSF, and that such cells are targets for virus infection. The present work also demonstrates that the leukocyte population changes, such as B lymphocyte depletion and the relative dominance of myeloid cells in the blood during CSF, occur before virus infection of the affected cells. Thus, the pathological mechanism therein is not a direct consequence of virus infection.

Erroneous monocyte and neutrophil counts with the Sysmex NE-1500 in patients recovering from bone marrow aplasia.

The Sysmex NE-1500 is a haematological analyser which offers five-part differential counts. The instrument was submitted to an extensive evaluation procedure before acceptance to the laboratory and was found to perform satisfactorily. However, problems arose in clinical practice with the analysis of samples from patients recovering from bone marrow aplasia. Falsely low monocyte counts and, controversely, falsely high neutrophil counts were found in these patients. Only a minority (13%) of these samples were flagged as abnormal by the instrument. The most alarming consequence of these results is the overestimation of neutrophils and the exclusion of these patients from reimbursement for treatment with growth factors. We conclude that in patients recovering from aplasia, differential counts performed with the Sysmex NE series should always be checked manually.

Predictive markers in the late gestation period for retained placenta in black-pied dairy cows under field conditions in France

A prospective ecopathogical survey was conducted in French commercial dairy herds located in Brittany. Previous production and reproduction data and blood parameters were used to identify predictive indicators of risk for retained placenta (RP) in Black-Pied cows. All the cows had delivered a single calf after a dry period of at least 30 d and had produced milk for at least 30 d. The cows with and without retained placenta were allocated to groups according to herd and interval between antepartum blood sampling and calving. Two groups of cows with (RP-positive group, n=45) and without (RP-negative group, n=184) retained placenta were compared. Univariate analysis indicated lower plasma glucose concentration, lower monocyte count and higher red blood cell count in the RP-positive group. A multiple logistic regression was run, with herd and blood sampling to calving interval as the fixed effects. It showed that a high red cell count and a low monocyte count were predictive indicators for retained placenta risk, which was found to be lower at third calving. Relationships of circulating indicators with placental retention etiology are discussed in terms of polyunsaturated fatty acid imbalance, its consequences on monocyte and erythrocyte functions, uterine motility and circulatory disturbances.

Low HLA-DR expression on monocytes as a prognostic marker for bacterial sepsis after liver transplantation.

Low HLA-DR expression on monocytes is associated with an increased risk of infection after surgery or trauma. We determined the value of this parameter as a marker for sepsis after liver transplantation. The percentage of monocytes expressing HLA-DR was determined by flow cytometry before and after liver transplantation in nine patients. Five lung and 20 kidney transplant recipients served as controls. Bacterial sepsis occurred in 5 of 9 liver transplant patients and 0 of 24 control patients. Monocyte HLA-DR expression decreased <50% in all five patients with sepsis. HLA-DR expression dropped before (n=4) or at the time of sepsis (n=1), and remained low for 13 weeks. HLA-DR expression remained >50% in the four liver transplant patients without sepsis. Only 1 of 25 control patients had persistently low monocyte HLA-DR expression. Monitoring of monocyte HLA-DR expression may be helpful in identifying liver transplant patients who have an increased risk of imminent bacterial sepsis.

Low Density Lipoprotein-Apheresis Decreases Oxidized Low Density Lipoproteins and Monocyte Adhesion to Endothelial Cells

The mutual interaction between monocytes and low density lipoprotein (LDL) in atherogenesis prompted a test of the hypothesis that LDL-apheresis could reduce the adhesive properties of monocytes to endothelium; and therefore interfere with a key mechanism in atheroma formation. Five patients affected by heterozygous familial hypercholesterolemia were studied. All patients received LDL-apheresis treatment with selective adsorption of LDL-cholesterol on dextran-sulphate columns. Low density lipoprotein particles were isolated by sequential preparative ultracentrifugation and subfractionated by ion exchange high performance liquid chromatography. Thiobarbituric acid reacting products of lipid peroxidation were measured fluorometrically. Vitamin E was estimated by high performance liquid chromatographic technique. Monocytes were isolated from patients blood before and 1 day after LDL-apheresis by Percoll gradient. The blood samples for monocyte adhesion were drawn from control subjects for 2 consecutive days. The adhesion of monocytes to an endothelial monolayer was evaluated by assaying the peroxidase content of the adherent monocytes. Low density lipoprotein-apheresis reduced total cholesterol (-65%; p < 0.01), LDL-cholesterol (-75%; p < 0.01), triglycerides (-51%; p < 0.05), and fibrinogen (-28%; p < 0.01). With LDL-apheresis treatment, a reduction of 54% in oxidized LDLs was observed; vitamin E concentration significantly increased in LDLs (+ 14.2%; p < 0.05). The monocyte adhesion decreased by approximately 61% after apheresis; the variation became statistically significant (-65%; p < 0.01) when endothelial cells were stimulated by lipopolysaccaride.

Low Density Lipoprotein-Apheresis Decreases Oxidized Low Density Lipoproteins and Monocyte Adhesion to Endothelial Cells

Low Density Lipoprotein-Apheresis Decreases Oxidized Low Density Lipoproteins and Monocyte Adhesion to Endothelial Cells

Low Bone Mineral Density and Peripheral Blood Monocyte Activation Profile in Calcium Stone Formers with Idiopathic Hypercalciuria

Low Bone Mineral Density and Peripheral Blood Monocyte Activation Profile in Calcium Stone Formers with Idiopathic Hypercalciuria

Low bone mineral density and peripheral blood monocyte activation profile in calcium stone formers with idiopathic hypercalciuria.

Calcium stone formers (CaSF) with idiopathic hypercalciuria (IH) have been shown to have decreased bone mineral density (BMD). The mechanism of their bone loss remains obscure. Monokines like interleukin-1 beta (IL-1 beta), IL-6, tumor necrosis factor-alpha (TNF-alpha), and granulocyte macrophage stimulating factor (GM-CSF) are involved in bone remodeling, but only IL-1 excess has been incriminated in the bone loss of CaSF with IH. Therefore, to more precisely delineate the role of monocyte activation in the pathogenesis of bone loss in these patients, we studied the production of IL-1 beta, IL-6, TNF-alpha, and GM-CSF by unstimulated or lipopolysaccharide (LPS)-stimulated cultured peripheral blood monocytes in 15 CaSF with IH, in 10 CaSF with dietary calcium-dependent hypercalciuria (DH), and in 10 healthy controls (C). Cytokines were measured in the culture medium by sensitive enzyme-linked immunosorbent assay and vertebral BMD by single energy computed tomography. The decrease of vertebral BMD in IH compared with DH, was confirmed (Z score: -1.2 +/- 0.2 vs. -0.5 +/- 0.2; P = 0.04; Mann-Whitney). In the supernatant of unstimulated peripheral blood monocytes, IL-1 beta and TNF-alpha levels were higher in IH than in C (respectively, 40 +/- 21 vs. 7 +/- 1 pg/mL, P = 0.008 and 236 +/- 136 vs. 39 +/- 23 pg/mL, P = 0.03); those of GM-CSF were greater in IH than in DH and C (respectively, 52 +/- 27 vs. 6 +/- 2, P = 0.04 and 6 +/- 2 pg/mL, P = 0.01) and those of IL-6 were not significantly different among the groups. After in vitro stimulation by LPS (10 micrograms/mL), the levels of the various monokines were not significantly different. In IH patients, the post-LPS levels of IL-6 were negatively correlated to vertebral BMD (n = 15, Z = -1.97, P = 0.04; Spearman), whereas those of GM-CSF were positively related to vertebral BMD (n = 15, Z = 2.01, P = 0.04). In this study, calcium stone formers with IH have bone mineral decrease and a particular profile of peripheral blood monocytes activation. This latter is characterized by a spontaneously increased synthesis of IL-1 beta, TNF-alpha, and GM-CSF. Furthermore, post-LPS levels of IL-6 and GM-CSF are correlated with vertebral BMD. These results suggest that monocyte activation may be involved in the bone loss of calcium stone formers with IH.

Genetic determinants of mortality in acute necrotizing pancreatitis

Acute necrotizing pancreatitis (ANP), which often progresses to infection, sepsis, and multisystem organ failure, runs a course remarkably similar to that seen frequently after severe burns, massive physical trauma, or major surgery. There is extensive evidence that the development of the sepsis response is mediated by immunocytes, particularly activated polymorphonuclear leukocytes (PMNLs) and their secretions (reactive oxygen species, lysosomal hydrolases, cytokines, and so on). Some years ago it was suggested that the high mortality of ANP may be related to an overaggressive immunological defense system of the host rather than to autodigestion of the gland. Recent investigations of the immunoregulatory responses following surgery or other trauma have not only furnished additional support for this concept, but also revealed some genetic factors that may critically influence the outcome of posttraumatic illness including ANP. The prognostic significance of abnormal, early polymorphonuclear leukocyte (PMNL) activation in the development of sepsis, high neutrophil expression of certain receptor molecules, low monocyte and lymphocyte expression of major histocompatibility antigen MHC-class II, and the influence of the genetically encoded TNF and IL-1 secretion on the course of the illness are discussed and related to ANP. Evidence is presented for the potential usefulness of some of these parameters in the prognosis and future treatment of ANP.

Decreased reactivity to PPD among HTLV-I carriers in relation to virus and hematologic status.

Data on human T-cell lymphotropic-virus-type-I (HTLV-I) status and hematology from 528 individuals were analyzed for associations with low reactivity to the purified protein derivative (PPD) of Mycobacterium tuberculosis recall antigen. Subjects were classified as HTLV-I carriers with abnormal lymphocytes (Ably), carriers without Ably, and seronegatives. All carriers had a significant 2.6-fold risk of being low responders to PPD compared with the seronegatives, carriers with Ably having the highest relative risk. Carriers with HTLV-I-antibody titer > or = 1:256, or with other detectable markers of virus status such as antibody to tax and proviral DNA, had increased risk for low response to PPD similar to the estimate for HTLV-I seropositivity alone, compared with the seronegatives. Subjects with a low lymphocyte count had 3.5 times the risk for being low responders to PPD, compared with subjects with high counts. Similarly, subjects with a low monocyte count had 2.0 times the risk for low reactivity of those with a moderate to high count. Results were not confounded by age, sex, smoking or alcohol drinking. Using multiple logistic regression, only HTLV-I seropositivity and low lymphocyte and monocyte counts were predictive of low reactivity to PPD. Analysis indicates that suppression of delayed-type hypersensitivity is associated with HTLV-I infection per se, and not with viral replication or load. Furthermore, this effect may occur in part via changes in the number and function of lymphocytes and monocytes. Such a mechanism may involve altered cytokine production in carriers and concomitant changes in cell populations involved in delayed-type hypersensitivity.

Calcium regulation of endothelial permeability to low density lipoprotein and U937 monocytes: J. Jeffrey Alexander, MD, Remedios Miguel, MS, and Joseph J. Piotrowski, MD, Case Western Reserve University, Cleveland, Ohio

Calcium regulation of endothelial permeability to low density lipoprotein and U937 monocytes: J. Jeffrey Alexander, MD, Remedios Miguel, MS, and Joseph J. Piotrowski, MD, Case Western Reserve University, Cleveland, Ohio

A 21-aminosteroid inhibits oxidation of human low density lipoprotein by human monocytes and copper

Oxidation of low density lipoprotein (LDL) leads to more rapid uptake by arterial wall macrophages and foam cell formation. Inhibiting LDL oxidation may impede these processes and offers a new mechanism to retard atherogenesis. The 21-aminosteroids, derived from methylprednisolone, are potent inhibitors of free radical production by stimulated monocytes and also are scavengers of lipid peroxyl radicals. The 21-aminosteroid, U74500A, was added to a mixture of low density lipoprotein cholesterol and human monocytes to which lipopolysaccharide was add to stimulate the monocytes. At a final concentration of 10 μM, U74500A reduced the production of lipid peroxidation from 6.10 ± 1.11 to 0.84 ± 0.16 nmol (mean ± SEM) MDA equivalent/1 × 10 6 monocytes, as measured by a thiobarbituric acid reacting substance (TBARS) assay. Similarly 10 μm U74500A reduced Cu 2+ induced LDL oxidation from 12.28 ± 0.10 (in vehicle) to 0.49 ± 0.12. These observations suggest that the 21-aminosteroids should be evaluated in animal models as a potential therapy to retard atherogenesis, especially considering their apparent lack of mineralocorticoid and glucocorticoid side-effects.

Monocyte zinc andIn vitro prostaglandin E2 and interleukin-1? production by cultured peripheral blood monocytes in patients with Crohn's disease

This study investigated the relationship between zinc status and prostaglandin E2 and interleukin-1 beta production by cultured monocytes in patients with Crohn's disease. Monocyte zinc was significantly decreased in both 12 inpatients and 22 outpatients compared with controls (P less than 0.001) but lymphocyte and polymorphonuclear cell zinc were normal. When cultured monocytes from 10 outpatients with Crohn's disease were stimulated with lipopolysaccharide, prostaglandin E2 production increased markedly, coupled with a fall in monocyte zinc. In matched controls, prostaglandin E2 production was significantly less and monocyte zinc remained stable. No difference in interleukin-1 release was noted between patients and controls. The addition of prednisolone to cell cultures suppressed prostaglandin E2, interleukin-1 synthesis, and monocyte zinc did not change. Zinc chloride augmented prostaglandin E2 production in patients, but not controls, and interleukin-1 remained stable. These results demonstrate a link between low monocyte zinc concentration and excessive prostaglandin production in patients with Crohn's disease.

Suppression of tumor cell susceptibility to monocyte-induced cell death by growth-inhibitory signals generated during monocyte/tumor cell interaction

In a recently established serum-free in vitro system it has been demonstrated that the susceptibility of various human tumor cells to the induction of cell death by elutriated human monocytes is critically dependent on tumor cell density and growth state. In the present work it is shown by flow cytofluorometric analysis of bromodeoxyuridine incorporation rates and of expression of the proliferation-associated nuclear antigen Ki-67, that tumor cells forced out of the cell cycle into the quiescent state (G0), which can be accomplished by treatment with supernatant from monocyte/tumor cell interaction cultures, are no longer susceptible to the induction of cell death by monocytes. This suggests that processes essential for the lytic pathway cannot take place in quiescent cells. It is furthermore demonstrated that tumor cells are driven into G0 during interaction with monocytes and that the rate of transit from G1 to G0 increases with increasing monocyte dosage. This explains our earlier finding that maximum rates of tumor cell death are induced at rather low monocyte:tumor cell ratios of around 1:2 and that lysis is suppressed at higher monocyte dosages (van der Bosch et al.:Exp Cell Res 187:185-192, 1990). The potential significance of these findings for the supposed function of mononuclear phagocytes in tumor defense lies in the notion that tumor cells driven into G0 might escape this control and that signals involved in monocyte/tumor cell-interaction contribute to the accumulation of tumor cells in G0.

Density-dependent tumor cell death and reversible cell cycle arrest: Mutually exclusive modes of monocyte-mediated growth control

The population development of five human tumor cell lines is examined under the influence of elutriator-prepared human monocytes in a serum-free hormone- and growth factor-supplemented medium. Analysis was performed by electronic counting and sizing of tumor cell nuclei and flow cytometric detection of cell cycle phases. Tumor cell death is triggered at rather low monocyte:tumor cell ratios (1:2 to 1:4) whereas it is strongly reduced at high monocyte densities. Furthermore, it is shown that confluence of the target cell population is a necessary prerequisite for lysis. The data suggest that in monocyte/tumor cell cocultures the decision on target cell lysis is not made by the effector cell, but rather by the target cell and that the criterion for this decision is the target cell's ability or inability to respond to a monocyte challenge by arresting the cell cycle in G 1. Interactions between target cells play an important role in determining the result of this decision process. A common basis is suggested for this kind of density-dependent monocyte-triggered lysis and density-dependent cell death in 3T3 cell cultures as described previously.

Proteolysis induces increased binding affinity of the monocyte type II FcR for human IgG.

Human monocytes express two types of IgG FcR, Fc gamma RI and Fc gamma RII. These can be assayed by using indicator E sensitized by human IgG (EA-human IgG) or mouse IgG1, (EA-mouse IgG1), respectively. On mouse macrophages, Fc gamma RI is sensitive to trypsin, whereas Fc gamma RII is trypsin resistant. We studied the effects of the proteolytic enzymes pronase and trypsin on human monocyte Fc gamma R. Neither enzyme caused a decrease in rosetting mediated by monocyte Fc gamma RI. Human Fc gamma RII is polymorphic, and monocytes interact either strongly or weakly with mouse IgG1. The interaction of low responder monocytes with mouse IgG1 was dramatically increased (to the level exhibited by high responder monocytes) by protease treatment. The effects of proteases on Fc gamma RII were investigated in more detail by using monocytes from which Fc gamma RI was selectively modulated by using immobilized immune complexes. Proteolysis of such modulated monocytes induced an increased interaction with EA-human IgG. Fc gamma RII appears to mediate this interaction. This conclusion is supported by the observation that after proteolysis, the Fc gamma RII-mediated binding of EA-mouse IgG1 becomes susceptible to inhibition by (monomeric) human IgG. To quantify the effect of proteolytic enzymes on Fc gamma RII, we performed binding studies with cell line K562, that expresses only Fc gamma RII. A significant increase in Ka of Fc gamma RII for dimeric human IgG complexes was observed when K562 cells were treated with protease. To elucidate the mechanism of this enhancement of Ka by proteolysis, we performed immunoprecipitation studies. Neither m.w., nor IEF pattern of Fc gamma RII were influenced by proteolysis. Moreover, the expression of Fc gamma RII was not affected by proteolysis as evidenced by immunofluorescence studies and Scatchard analysis, and neither were Fc gamma RI or Fc gamma RIII induced. We conclude that proteolysis increases the affinity of Fc gamma RII for human IgG, and speculate that such a proteolysis-induced change may also occur in vivo, e.g., at inflammatory sites.