Inflammatory/haematopoietic cytokine production by human bone marrow adipocytes.

Adipocytes are now considered as secretory and endocrine cells. White and brown adipocytes synthesize and secrete a variety of cytokines, among a number of peptide and non-peptide products. Some of these cytokines, particularly IL-6 and TNF-alpha, appear multifunctional since they may be involved in the control of adipose mass, inflammatory response and haematopoiesis. Bone marrow adipocytes are another abundant type of adipocytes, but their precise role in humans is poorly understood. In the present study, we demonstrate that, in contrast to non-medullary adipocytes, human bone marrow adipocytes in primary culture secrete only trace amounts of IL-1 beta and TNF-alpha, but, they secrete significant and regulated levels of IL-6. These results reinforce the concept of functional heterogeneity of adipose tissues according to their anatomical localization, and indicate that bone marrow adipocytes may contribute to the complex network of cytokines involved in the control of haematopoiesis.

Regulation by cytokines of leptin expression in human bone marrow adipocytes.

Leptin is a hormone secreted by adipocytes. Besides controlling appetite and body weight, it has been suggested that leptin plays a role in inflammation and hemopoiesis. In this study we demonstrate that the pro-inflammatory/hemopoietic cytokines, IL-1beta, IL-6, TNF-alpha, and interferon-gamma, significantly inhibit gene expression and secretion of leptin by bone marrow adipocytes. These findings are in agreement with the data recently obtained from non-medullary adipose tissues. Within the bone marrow environment, leptin regulation by these pleiotropic cytokines could contribute to controlling the proliferation and differentiation of hemopoietic precursors as well as the maturation of stromal cells.

High concentration of leptin stimulates myeloid differentiation from human bone marrow CD34+ progenitors: potential involvement in leukocytosis of obese subjects.

OBJECTIVE AND DESIGN: As well as its involvement in control of adipose mass and body energy balance, several reports suggest a link between leptin and hemopoiesis. To test its putative role in human hemopoiesis, we developed a homologous system, ie recombinant human leptin treatment of purified CD34+ progenitors from adult human bone marrow. RESULTS: Leptin (50-100 ng/ml) significantly stimulated the appearance of granulocyte-macrophage colonies in the presence or absence of erythropoietin. The concentration of leptin required for this effect was rather high but within the range of plasma leptin levels observed in obesity. Two results further support the hypothesis that leptin may be involved in the leukocytosis associated with obesity: (i) leptin concentrations in bone marrow and plasma of subjects studied were highly correlated; (ii) leptin and leukocyte count were correlated only in obese subjects. Paracrine effects of locally released leptin from bone marrow adipocytes could also be involved in the regulation of hemopoiesis, a hypothesis supported by marrow immunocytochemistry revealing the close association of CD34+ cells with adipocytes and by previous demonstration that leptin is secreted at a high level by these cells. CONCLUSION: These results indicate that leptin acts on human multilineage CD34+ cells and that high plasma leptin levels associated with obesity could participate in the differentiation of granulocytes from hemopoietic progenitors.

Evaluation of the Vega haematology analyser in a university hospital setting.

The performance of the ABX Vega haematology analyser was compared with that of the Sysmex NE-8000, with specific attention to flagging performance and ergonomics. Eight hundred routine samples underwent precision and interinstrument variability studies and 168 samples corresponding to various blood disorders were studied meanwhile. Results from the two instruments gave excellent correlation (r > 0.900) for most parameters except MCHC (r = 0.114), basophil and monocyte percentages (r = 0.617 and 0.552, respectively). The reproducibility, repeatability, linearity, carry-over and stability of the Vega were satisfactory; 'flagging' occurred in 31% of routine samples with sensitivity 88.8%, specificity 41.3% and positive predictive value 85.7%. Various flags appeared in 91% (42/46) of cases where blast cells were microscopically identified. In the four remaining cases, CBC anomalies would themselves have justified microscopic examination of a smear. On 'CBC only' mode reagent consumption was significantly reduced. In the laboratory the analyser was best appreciated for its user-friendliness.

A role for preadipocytes as macrophage-like cells.

Several lines of evidence have supported a link betweeen adipose tissue and immunocompetent cells. This link is illustrated in obesity, where excess adiposity and impaired immune function have been described in both humans and genetically obese rodents. In addition, numerous factors involved in inflammatory response are secreted by both preadipocytes and macrophages. Here we show that proliferating preadipocytes in cell lines and primary cultures, develop phagocytic activity toward microorganisms. This is demonstrated by phagocytosis assays and confocal microscopy. This function disappears when preadipocytes stop proliferating and differentiate into adipocytes. After phagocytosis, preadipocytes show microbicide activity via an oxygen-dependent mechanism. In addition, preadipocytes as well as adipocytes are stained with MOMA-2, a marker of monocyte-macrophage lineage, but are negative for specific mature macrophage markers (F4/80 and Mac-1). These results suggest that preadipocytes could function as macrophage-like cells and raise the possibility of a potential direct involvement of adipose tissue in inflammatory processes.

High expression of leptin by human bone marrow adipocytes in primary culture.

Adipocytes participate in the microenvironment of the bone marrow (BM), but their exact role remains to be determined. It has recently been shown that leptin, a hormone secreted from extramedullary adipocytes, could be involved in hematopoiesis. Therefore we have developed a primary culture system of human BM adipocytes to characterize their differentiation and determine whether leptin is also secreted from these adipocytes. BM cells were cultured with fetal calf and horse sera. In the presence of dexamethasone, cells with vesicles containing lipids appeared within 15 days. They expressed glycerol phosphate dehydrogenase activity and a lipolytic activity in response to isoproterenol, but expressed neither the adrenergic beta3 receptor nor the mitochondrial uncoupling protein UCP1. The addition of insulin alone to the culture media did not promote adipocyte differentiation. Leptin was expressed and secreted at high levels during adipocyte differentiation. Acute exposure of differentiated adipocytes to insulin had little effect on leptin expression whereas forskolin strongly inhibited it. These results show that although human BM adipocytes differ from extramedullary adipose tissues in their sensitivity to different effectors, they are a secondary source of leptin production. They suggest that BM adipocytes could contribute to hematopoiesis via the secretion of leptin in the vicinity of hematopoietic stem cells.

Isolation of bone marrow plasma cells by negative selection with immunomagnetic beads.

In order to isolate bone marrow plasma cells from patients presenting with multiple myeloma or monoclonal gammopathy of undetermined significance, we developed a method for purifying these cells by negative selection using monoclonal antibodies and immunomagnetic beads. The results presented here were obtained from 75 procedures. Purity was extremely variable (2-100%) and was dependent on the percentage of plasma cells in the original bone marrow sample with a 10% cut-off, beyond which purity was over 96% in all cases. The mean yield was about 20%. The cells collected were viable and suitable for immunophenotyping, semi-quantitative studies of oncoproteins, and PCR.

New antibody in severe rhesus incompatible pregnancies: IgG-kappa antiplacental alkaline phosphatase.

As already found in other various diseases, a macromolecular alkaline phosphatase complex (HMW-AP) was also found in sera of two severe Rhesus-incompatible pregnancies complicated by ascites and fetal hydrops at delivery. This atypical complex was detected and isolated by agarose gel electrophoresis. Immunoelectrophoresis and heat inactivation of this HMW-AP complex revealed that it consisted of IgG of the kappa type and placental AP isoenzyme. The transitory presence of this immuncomplex is discussed. However, in all women with Rh-immunized complicated pregnancies, significant variations of neutrophil and serum AP activities were observed. A fall in AP activity and the presence of an antiplacental AP antibody in serum of women with complicated Rh immunization should be of value in assessing the prognosis of the disease.

Characterization of alkaline phosphatase in polymorphonuclear neutrophils from normal sheep.

This paper is an attempt to the analysis of the main biochemical characteristics of alkaline phosphatase from sheep polymorphonuclear neutrophils. Ten male adult Romanoff X Berrichon sheep were studied. Alkaline phosphatase was analyzed from cell homogenates, after extraction and solubilization steps. The Vmax and Km values for 4-nitrophenylphosphate at pH = 9.80 were 347.3 +/- 34 IU/ml and 0.7 +/- 0.18 mmol/l, respectively. The pH optimum was 9.80 with 4-nitrophenylphosphate. L-Homoarginine and EDTA, but not L-phenylalanine, inhibited the enzyme. Magnesium above a concentration of 0.5 mmol/l has shown a protective effect against inhibition by 115, 156 and 250 mmol/l urea (final concentration). Sheep neutrophil alkaline phosphatase was found to be very heat-labile. Polyacrylamide gel electrophoresis indicated a single band of activity with a relative mobility similar to that of the slow component of bone and liver isozymes. It is suggested from the above results that sheep neutrophil alkaline phosphatase shares several biochemical properties similar to those of hepatic bone tissue isozyme.

Polymorphonuclear dysfunction in bronchopulmonary diseases in human adults.

Polymorphonuclear (PMN) functions were assessed in 55 patients with asthma or bronchial bacterial infection to evaluate the systemic phagocyte capability of patients with bronchopulmonary diseases. Random migration, nitroblue tetrazolium dye reduction, and Candida killing activity were markedly decreased in the 2 types of patients studied. PMN dysfunction was more pronounced in the most affected and heavily treated patients. Considering both the rare occurrence of congenital polymorphonuclear defects and the age of the patients studied we concluded that the PMN abnormalities observed were secondary to the onset of respiratory disease. This impairment of circulating phagocytes may contribute to the rise of a systemic susceptibility to infection able to aggravate the underlying bronchopulmonary disease.

[Effect of ethanol on human polynuclear neutrophils. In vitro and in vivo study]. / Effet de l'éthanol sur les polynucléaires neutrophiles humains. Etude in vitro et in vivo.

Human polynuclear neutrophilic function was studied to determine the role of alcohol in the increased susceptibility to infection of chronic alcoholics: in vitro studies investigated the effects of different concentrations of ethanol; in vivo studies included comparison with healthy subjects after alcohol intake, with excessive drinkers without liver disease and with chronic alcoholics with confirmed cirrhosis. In vitro depression of polynuclear neutrophilic function was observed only with significantly higher concentrations of ethanol than encountered clinically. In social and excessive drinkers, phagocytosis was decreased but there was no change in bactericidal activity. On the other hand, in cirrhotic alcoholics chemotaxis, phagocytosis and bactericidal activity were all significantly reduced. A direct action of alcohol alone on polynuclear function would not seem to be the cause of the increased risk of bacterial infection of chronic alcoholics.

In vitro effect of the slime of Pseudomonas aeruginosa on the function of human polymorphonuclear neutrophils.

The slime of Pseudomonas aeruginosa markedly impaired the in vitro motility, endocytosis, and phagosome formation of normal human polymorphonuclear neutrophils. This profound impairment of neutrophils, although without alteration of their viability, may contribute to the virulence of this microorganism.

Impairment of polymorphonuclear functions in hospitalized geriatric patients.

Polymorphonuclear (PMN) functions were assessed in 93 non-selected hospitalized patients, 32 active, healthy, elderly controls and 29 young controls. The results confirm the impairment of PMN functions in the aged. However, PMN functions in hospitalized older persons are similar to those in non-institutionalized controls, and underlying diseases and treatment do not seem to aggravate the PMN impairment. Thus, it can be assumed that the frequent and severe infections afflicting the hospitalized aged are due to the alteration of the other host-defense mechanisms.

Polymorphonuclear functions and aging in humans.

To determine whether normal aging interferes with the functional capability of polymorphonuclear leukocytes (PMNs), 6 tests of PMN function were performed in 285 healthy subjects whose ages ranged from 20 to 97 years. A second selection based upon blood measurement and a review of medical histories 6 months later, eliminated 68 subjects. The 217 remaining persons were sub-classed by age into 7 groups including equal numbers of males and females. The functional properties of PMNs in the aged, when compared to those of younger adults, were characterized by: (a) a decrease in the chemotactic response in the 80+ age group: (b) increased adherence, with onset after age 70, maximal after age 80; (c) a progressive decrease of NBT dye reduction capability, up to age 70-79, followed by an unexplained increase of the mean value after age 80; (d) diminished Candida-killing activity, appearing in the 60+ group and becoming lowest in the oldest group; and (e) lack of changes in spontaneous migration and endocytosis. The mechanisms by which this impairment occurs are hypothetical. It is proposed that normal PMNs, after leaving the bone marrow, are influenced by various humoral components such as metabolic byproducts or immune processes altered by aging. Thus the defective PMN may represent only another victim of the aging process.

Effect of tobacco smoking on the functions of polymorphonuclear leukocytes.

Eight tests investigating the function of circulating polymorphonuclear leukocytes were performed in 68 subjects, half of whom smoked at least 20 cigarettes per day. Comparison of the two groups allowed determination of the in vivo effect of tobacco smoke on the nonspecific defense system of the body. Ingestion ability, oxygen consumption, and bactericidal activity were normal in smokers. Myeloperoxidase and neutrophil alkaline phosphatase activities also were unchanged. The nitroblue tetrazolium reduction and the serum lysozyme levels were slightly increased in smokers. The capillary tube random migration, though, was depressed, and intensive smoking further aggravated this change. It is suggested that tobacco smoke acts directly on one (or several) unidentified target site of polymorphonuclear leukocytes. This impairment, demonstrated in vivo, probably plays a role in the genesis of the bronchopulmonary diseases so frequent in heavy smokers.