Cultures Of Human Blood Monocytes Research Articles

Antiatherogenic effect of grape flavonoids in an ex vivo model

The effects of grape phytoestrogens on cholesterol accumulation were studied in primary culture of human blood monocytes incubated with blood serum from postmenopausal women obtained before and 2, 4, and 6 h after single intake of plant components of grapes. Phytoestrogens from grape seeds, pressed out grapes, and fermented grape ridges prevent cholesterol accumulation in cells and can be regarded as prospective components for the development of natural preparations for the prevention of atherosclerosis in postmenopausal women.

The effects of beta 2-adrenoceptor agonists and a corticosteroid, budesonide, on the secretion of inflammatory mediators from monocytes.

1. The in vitro effects of the beta 2-adrenoceptor agonists (1 x 10(-9)-10(-5) M), terbutaline, salmeterol, and formoterol, on the release of inflammatory mediators, i.e. the eicosanoids leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) and the cytokine interleukin-1 beta (IL-1 beta), were assessed in cultures of human blood monocytes. For comparison, the effects of a 5-lipoxygenase inhibitor, BW A4C (1 x 10(-9)-10(-5) M), and a corticosteroid, budesonide (1 x 10(-10)-10(-5) M) were also examined. Sotalol was used to investigate whether the actions of beta 2-agonists were mediated through beta-adrenoceptors. 2. Terbutaline, like budesonide, had no significant effect on LTB4 release, whereas BW A4C (IC50 = 2 x 10(-8) M) was a potent inhibitor. All concentrations of formoterol approximately halved the LTB4 secretion, whereas high concentrations (1 x 10(-7)-10(-5) M) only, of salmeterol, inhibited release. Only salmeterol, at high concentrations (greater than 1 x 10(-6) M), lowered the secretion of PGE2 in monocyte cultures. Formoterol and salmeterol reduced the secretion of IL-1 beta only at the highest dose (1 x 10(-5) M). In contrast, budesonide (greater than or equal to 1 x 10(-9) M) was a potent suppressant of this secretion. 3. Treatment of monocyte cultures with sotalol (1 x 10(-5) M) did not significantly antagonize the inhibitory effects of salmeterol and formoterol. These results suggest that the inhibitory action of these beta 2-agonists on the release of eicosanoids or IL-1 beta, is not mediated via beta 2-adrenoceptors.4. This study does not support a therapeutic importance of the anti-release effects of beta2-agonists since high concentrations were generally required. Furthermore, the anti-secretory action of beta2-agonists was distinct from that of corticosteroids.

Effects of cytokines on the production of lipoprotein lipase in cultured human macrophages.

Macrophages are important cells in the pathogenesis of atherosclerosis because of their tendency to accumulate lipid and become transformed into foam cells. Cultured human monocyte-derived macrophages spontaneously secrete lipoprotein lipase (LPL), and LPL has been linked to increased lipid uptake by these cells. Because secretion of various macrophage products depends on activation by lymphokines, we studied the effects of immunoregulatory lymphokines on LPL secretion by cultured human macrophages. After culturing cells in RPMI 1640 medium with 20% fetal calf serum, recombinant human gamma-interferon (gamma-INF), interleukin-1 (IL-1), and interleukin-2 (IL-2) were added to the medium and LPL secretion was assessed by measuring LPL activity and/or LPL mass in the medium. Gamma-INF suppressed LPL production both when added to freshly plated cultures of human blood monocytes, as well as when added to monocyte/macrophages from mature cultures (day 6) that were producing large amounts of LPL. IL-1 inhibited medium LPL when added to freshly plated cultures, but not when added to mature cultures. On the other hand, IL-2 did not inhibit LPL in freshly plated cultures, but produced a dose-dependent suppression of LPL from mature cultures. None of the cytokines were cytotoxic to macrophages, and cells that were cultured in gamma-INF demonstrated partial recovery from LPL-suppressive doses of the cytokine. After exposure of cells to 50 U/ml of gamma-INF and 50 U/ml of IL-2 for 3 days, LPL mRNA levels, when expressed as LPL/gamma-actin ratios, were 42% and 53% of controls, respectively. Thus, activation of human macrophages in vitro by gamma-INF resulted in a suppression of LPL production.(ABSTRACT TRUNCATED AT 250 WORDS)

Minactivin expression in human monocyte and macrophage populations

Adherent monolayer cultures of human blood monocytes, peritoneal macrophages, bone marrow macrophages, and colonic mucosa macrophages were examined for their ability to produce and secrete minactivin, a specific inactivator of urokinase-type plasminogen activator. All except colonic mucosa macrophages produced and secreted appreciable amounts of minactivin, but only blood monocytes were stimulated by muramyl dipeptide (adjuvant peptide) to increase production. The minactivin from each of these populations could be shown to preferentially inhibit urokinase-type plasminogen activator and not trypsin, plasmin, or “tissue”-type plasminogen activator (HPA66). A plasminogen-activating enzyme present in monocyte cultures appeared unaffected by the presence of minactivin and could be shown to be regulated independently by dexamethasone.

Minactivin Expression in Human Monocyte and Macrophage Populations

Adherent monolayer cultures of human blood monocytes, peritoneal macrophages, bone marrow macrophages, and colonic mucosa macrophages were examined for their ability to produce and secrete minactivin, a specific inactivator of urokinase-type plasminogen activator. All except colonic mucosa macrophages produced and secreted appreciable amounts of minactivin, but only blood monocytes were stimulated by muramyl dipeptide (adjuvant peptide) to increase production. The minactivin from each of these populations could be shown to preferentially inhibit urokinase-type plasminogen activator and not trypsin, plasmin, or "tissue"-type plasminogen activator (HPA66). A plasminogen-activating enzyme present in monocyte cultures appeared unaffected by the presence of minactivin and could be shown to be regulated independently by dexamethasone.

Rickettsia sennetsu in human blood monocyte cultures: similarities to the growth cycle of Ehrlichia canis

Microscopic examination of cultured human monocytes infected with Rickettsia sennetsu and stained by the Giemsa method revealed the presence of various organismal growth forms in the cytoplasm of the infected cells. The growth forms were loosely scattered individual organisms, clusters of organisms, various sizes of dense inclusion bodies in intact and vacuolated cytoplasm, and organisms in close proximity to disintegrated monocytes. The appearance and the morphology of these R. sennetsu growth forms were similar to those of Ehrlichia canis propagated in canine monocytes. Specific identification of R. sennetsu was made by staining cultured monocytes with fluorescein-conjugated globulins extracted from the pooled sera of patients recovering from sennetsu rickettsiosis. Mice infected with cultured R. sennetsu developed gross pathological changes indicative of infection, and the organism was demonstrated in their spleens, peritoneal macrophages, and mononuclear blood cells. Human monocyte culture appeared to be more sensitive than the previously used African green monkey kidney cell line (BSC-1) for the isolation of R. sennetsu from samples containing minute infectious quantities of this organism.