scholarly journals Leukotriene generation by eosinophils.

1982 ◽  
Vol 155 (2) ◽  
pp. 390-402 ◽  
Author(s):  
A Jörg ◽  
W R Henderson ◽  
R C Murphy ◽  
S J Klebanoff
Keyword(s):  
Arachidonic Acid ◽  
Calcium Ionophore ◽  
Leukotriene B4 ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
Eicosatetraenoic Acid ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionophore A23187 ◽  
Lipoxygenase Pathway ◽  
Leukotriene D4

Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spectra, spectral shift on treatment with lipoxygenase, incorporation of [14C]arachidonic acid, gas chromatography-mass spectrometry, and comparison of retention times on HPLC to authentic standards. The eosinophil products characterized were 5-(S), 12-(R)-dihydroxy-6-cis-8, 10-trans-14-cis-eicosatetraenoic acid (leukotriene B4) and its 5-(S), 12-(R)-6-trans and 5-(S), 12-(S)-6-trans isomers, 5-(S)-hydroxy-6-(R)-S-glutathionyl-7,9-trans-11, 14-cis-eicosatetraenoic acid (leukotriene C4) and its 11-trans isomer, and 5-(S)-hydroxy-6-(R)-S-cysteinylglycine-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene D4).

Human alveolar macrophage arachidonic acid metabolism

1988 ◽  
Vol 254 (6) ◽  
pp. C809-C815 ◽  
Author(s):  
G. P. Brown ◽  
M. M. Monick ◽  
G. W. Hunninghake
Keyword(s):  
Arachidonic Acid ◽  
Alveolar Macrophages ◽  
Biological Effects ◽  
Leukotriene B4 ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Lipoxygenase Pathway ◽  
Cyclooxygenase Inhibition ◽  
Human Alveolar Macrophage ◽  
Lipoxygenase Products

Metabolites of arachidonic acid are potent modulators of many biological events, and their release from macrophages appears to play an important role in immune and inflammatory processes. In addition, metabolites of the cyclooxygenase or lipoxygenase pathway exhibit distinct biological effects. We used a method to determine if human alveolar macrophages (HAM) could be selectively activated to release products of cyclooxygenase or lipoxygenase pathway of arachidonic acid. HAM obtained by bronchoalveolar lavage from individuals were [3H]arachidonic acid labeled and then stimulated with lipopolysaccharide (LPS) or Ca ionophore A23187. Essentially no arachidonate metabolites were released by unstimulated cells. LPS caused dose- and time-dependent release of arachidonate and only cyclooxygenase products; no lipoxygenase products were detected, even in presence of cyclooxygenase inhibition. Metabolites released in response to LPS included thromboxane B2, prostaglandins D2, F2a, E2, and hydroxyheptadecatrienoic acid. A23187 caused a rapid release of arachidonate and 5-lipoxygenase products, leukotriene B4 and 5-hydroxyeicosatetraenoic acid; no cyclooxygenase inhibition. This demonstrates that HAM are specifically activated to release metabolites derived from cyclooxygenase or lipoxygenase pathway of arachidonic acid. Additionally, shunting down an alternate pathway is not induced by use of inhibitors of either pathway. This suggests alveolar macrophages may enhance or suppress various inflammatory or immune processes in lung, in part, by selective release of various derivatives of arachidonic acid.

scholarly journals Toxoplasma gondii alters eicosanoid release by human mononuclear phagocytes: role of leukotrienes in interferon gamma-induced antitoxoplasma activity.

1994 ◽  
Vol 180 (5) ◽  
pp. 1637-1648 ◽  
Author(s):  
E C Yong ◽  
E Y Chi ◽  
W R Henderson
Keyword(s):  
Arachidonic Acid ◽  
Toxoplasma Gondii ◽  
Calcium Ionophore ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
Mononuclear Phagocytes ◽  
Human Macrophage ◽  
Ionophore A23187 ◽  
Lipoxygenase Inhibitor ◽  
Ifn Gamma

Toxoplasma gondii tachyzoites markedly alter the profile of eicosanoids released by human mononuclear phagocytes. Freshly isolated, 2-h adherent human monocytes release both cyclooxygenase (e.g., thromboxane [TX] B2, prostaglandin [PG] E2) and 5-lipoxygenase (e.g., leukotriene [LT] B4, LTC4) products of arachidonic acid metabolism after stimulation by the calcium ionophore A23187 or ingestion of opsonized zymosan particles or heat-killed T. gondii. However, after incubation with viable T. gondii, normal and chronic granulomatous disease monocytes release only the cyclooxygenase products TXB2 and PGE2 and fail to form LTB4, LTC4, or other 5-lipoxygenase products. Monocytes maintained in culture for 5 d lose this capacity to release TXB2 and PGE2 after incubation with T. gondii. T. gondii significantly inhibit calcium ionophore A23187-induced LTB4 release by monocyte-derived macrophages; heat-killed organisms do not affect this calcium ionophore A23187-induced release of LTB4. T. gondii-induced inhibition of LTB4 release by calcium ionophore A23187-stimulated monocyte-derived macrophage is reversed by interferon (IFN)-gamma treatment of the monolayers. LTB4 induced extensive damage to the cellular membranes and cytoplasmic contents of the organisms as observed by transmission electron microscopy. Exogenous LTB4 (10(-6) M) induced intracellular killing of ingested T. gondii by non-IFN-gamma-treated monocyte-derived macrophages. IFN-gamma-induced antitoxoplasma activity in monocyte-derived macrophages was inhibited by the selective 5-lipoxygenase inhibitor zileuton but not by the cyclooxygenase inhibitor indomethacin. These findings suggest a novel role for 5-lipoxygenase arachidonic acid products in human macrophage IFN-gamma-induced antitoxoplasma activity.

A comparison of antigen-induced and calcium ionophore A23187 induced contraction of isolated guinea pig trachea

1981 ◽  
Vol 59 (10) ◽  
pp. 1031-1038 ◽  
Author(s):  
John F. Burka ◽  
Nigel A. M. Paterson
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
The Other ◽  
Ionophore A23187 ◽  
Lipoxygenase Inhibitor ◽  
Lipoxygenase Pathway ◽  
Histamine Secretion ◽  
Other Hand

Ovalbumin (OA) and the calcium ionophore A23187 induced a dose-dependent contraction of guinea pig tracheal strips. The OA-induced contraction (of sensitized trachea) consisted of an initial peak contraction, maximal between 5 and 10 min, followed by a very gradual decline from the peak. On the other hand, A23187 induced a sustained contraction of the trachea with a more gradual onset. Both antigen- and A23187-induced contractions required the presence of extracellular calcium. The response was not reduced by delaying (up to 10 min) the addition of calcium, suggesting that the mechanism of antigen-induced contraction differs from that of antigen-induced histamine secretion from rat mast cells and human basophils. The 1st min of the OA-induced contraction was inhibited significantly by mepyramine (10−5 M) suggesting that histamine contributed to the contraction at this time point. In contrast, A23187-induced contraction was unaffected by mepyramine. On the other hand, both the A23187-induced contraction and the prolonged phase of the OA-induced contraction were enhanced by indomethacin, a cyclooxygenase inhibitor, and inhibited by phenidone, a cyclooxygenase–lipoxygenase inhibitor. This suggests that a product of the lipoxygenase pathway of arachidonic acid metabolism contributes to OA- and A23187-induced contraction of the guinea pig trachea.

scholarly journals Arachidonic acid metabolism by human monocytes. Studies with platelet-depleted cultures.

1983 ◽  
Vol 158 (2) ◽  
pp. 393-412 ◽  
Author(s):  
N A Pawlowski ◽  
G Kaplan ◽  
A L Hamill ◽  
Z A Cohn ◽  
W A Scott
Keyword(s):  
Arachidonic Acid ◽  
Calcium Ionophore ◽  
Human Monocyte ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Human Monocytes ◽  
Fold Reduction ◽  
Inflammatory Stimuli ◽  
Cell Fractions

Purified human monocytes release and metabolize endogenous arachidonic acid (20:4) from phospholipid stores when challenged with particulate inflammatory stimuli or the calcium ionophore A23187. Using radiolabeled cultures, the percentage of total [3H]20:4 released was similar with each type of stimulus. However, the spectrum of 20:4 metabolites differed. With opsonized zymosan (OpZ) or Sephadex beads coated with IgG immune complexes (Ig-beads), the predominant product was thromboxane (25% of the total) together with smaller amounts of other cyclo-oxygenase products and lipoxygenase metabolites. Levels of thromboxane synthesis by monocytes were comparable to those by platelets, as measured by radioimmunoassay. In contrast, exposure to the nonspecific agent A23187 led to mainly lipoxygenase products (70% of the total). Monocytes isolated from mononuclear cell fractions of peripheral blood contain platelets specifically rosetted to their surfaces. These platelet contaminants were removed by sequential incubations of monocytes in serum and EDTA followed by adherence and detachment from tissue culture vessels. The presence of platelets in routinely isolated monocytes presented a major difficulty in the study of human monocyte 20:4 metabolism since platelets also synthesize thromboxane. Loss of 12-HETE synthesis (16-fold reduction relative to 5-HETE) in A23187-stimulated cultures provided a convenient measure of platelet depletion. This together with the response to monocyte-specific stimuli (OpZ and Ig-beads) allowed for the distinction between monocyte and platelet 20:4 metabolism.

A23187 stimulates translocation of 5-lipoxygenase from cytosol to membrane in human alveolar macrophages

1992 ◽  
Vol 262 (4) ◽  
pp. L454-L458
Author(s):  
R. J. Pueringer ◽  
C. C. Bahns ◽  
M. M. Monick ◽  
G. W. Hunninghake
Keyword(s):  
Alveolar Macrophages ◽  
Membrane Fraction ◽  
De Novo ◽  
Calcium Ionophore ◽  
Leukotriene B4 ◽  
Calcium Ionophore A23187 ◽  
Eicosatetraenoic Acid ◽  
Ionophore A23187 ◽  
Protein Synthesis Inhibitors ◽  
Human Alveolar Macrophages

Human alveolar macrophages stimulated with the calcium ionophore A23187 selectively release large amounts of leukotriene B4 (LTB4) and (+/-)-5-hydroxy-(6E, 8Z-11Z, 14Z)-eicosatetraenoic acid. To determine whether LTB4 release by human alveolar macrophages following A23187 stimulation required the de novo production of 5-lipoxygenase, alveolar macrophages were stimulated under conditions that would preclude a role for new enzyme production. We found that A23187-stimulated alveolar macrophages release LTB4 within 10 min following stimulation, that LTB4 release is not inhibited by protein synthesis inhibitors, and that release of LTB4 does not correlate with the de novo synthesis of the first committed enzyme, 5-lipoxygenase. In contrast, LTB4 release correlated with the translocation of 5-lipoxygenase from the cytosol to the membrane fraction of the cells following A23187 stimulation and was inhibited by MK-886. These findings show that A23187 stimulation of alveolar macrophages results in translocation of a preexistent 5-lipoxygenase from the cytosol to the membrane fraction of the cell and that this translocation of 5-lipoxygenase is associated with release of LTB4 from the cells.

scholarly journals A selective defect in arachidonic acid release from macrophage membranes in high potassium media.

1984 ◽  
Vol 99 (4) ◽  
pp. 1235-1241 ◽  
Author(s):  
A A Aderem ◽  
W A Scott ◽  
Z A Cohn
Keyword(s):  
Arachidonic Acid ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Breakdown Product ◽  
Ionophore A23187 ◽  
Ligand Complex ◽  
High Potassium ◽  
Lipoxygenase Pathway ◽  
High K ◽  
High Concentrations

Murine peritoneal macrophages cultured in minimal essential medium (alpha-MEM; 118 mM Na+, 5 mM K+) released arachidonic acid (20:4) from phospholipids on encountering a phagocytic stimulus of unopsonized zymosan. In high concentrations of extracellular K+ (118 mM), 3H release from cells prelabeled with [3H]20:4 was inhibited 80% with minimal reduction (18%) in phagocytosis. The inhibitory effect of K+ on 20:4 release was fully reversed on returning cells to medium containing Na+ (118 mM). Preingestion of zymosan particles by macrophages maintained in high K+ medium resulted in cells being "primed" for 20:4 release, which was only effected (without the further addition of particles) by changing the medium to one containing Na+. In contrast, 20:4 release from cells stimulated with the calcium ionophore A23187 was unimpaired by the elevated K+ medium, suggesting no direct effect of high K+ on the phospholipase. Macrophages stimulated with zymosan in alpha-MEM metabolized the released 20:4 to prostacyclin, prostaglandin E2 (PGE2), and leukotriene C (LTC). The smaller quantity of released 20:4 in high K+ medium was recovered as 6-Keto-PGF1 alpha, the breakdown product of prostacyclin, and PGE2. No LTC was synthesized. In high K+, resting (no zymosan) macrophages synthesized hydroxyeicosatetraenoic acids from exogeneously supplied 20:4 in proportions similar to cells maintained in alpha-MEM. These findings and the similarity of products (including LTC) produced by A23187 stimulated cells in alpha-MEM and high K+ medium indicated that the cyclooxygenase and lipoxygenase pathway enzymes were not directly inhibited by high extracellular K+. We conclude that high concentrations of extracellular K+ uncouple phagocytosis of unopsonized zymosan from the induction of the phospholipase responsible for the 20:4 cascade and suggest that the lesion is at the level of signal transduction between the receptor-ligand complex and the phospholipase.

Inhibition of antigen and calcium ionophore A23187 induced contractions of guinea pig airways by isoprenaline and forskolin

1983 ◽  
Vol 61 (6) ◽  
pp. 581-589 ◽  
Author(s):  
John F. Burka
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Arachidonic Acid Metabolism ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Inhibitory Effects ◽  
Lipoxygenase Pathway ◽  
Low Concentrations ◽  
Peak Phase ◽  
Initial Peak

Isoprenaline and forskolin both inhibit contractions induced by antigen or by the calcium ionophore A23187 of guinea pig tracheal spirals and parenchymal strips. Antigen-induced airway contraction is considerably more sensitive to the inhibitory effects of isoprenaline than is A23187-induced contraction. In contrast, forskolin is equiactive as an inhibitor of antigenic and ionophoric contractions. Forskolin is a more effective inhibitor of the prolonged phase of antigen-induced tracheal contraction than of the initial peak phase, which may suggest selectivity for the lipoxygenase pathway of arachidonic acid metabolism. Isoprenaline inhibits the mechanisms of the primary peak phase and of the prolonged phase equally. Although there were little, if any, differences between normal and sensitized tissues in the modulation of A23187-induced contractions of parenchyma, distinct differences were observed in trachea. Low concentrations (10−8–10−7 M) of isoprenaline and forskolin enhanced A23187-induced contraction of sensitized, but not normal trachea. Higher concentrations were inhibitory. The results demonstrate that sensitization affects the modulation by isoprenaline and forskolin of A23187-indueed contraction of guinea pig trachea.

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