Sodium-potassium ATPase inhibition potentiates compound 48/80-induced histamine secretion from mast cells.

The effect of ouabain on the histamine secretion induced by compound 48/80 has been studied using rat peritoneal mast cells. Ouabain did not modify histamine release in the presence of millimolar concentrations of extracellular calcium. However, when mast cells were previously washed with a calcium-free buffer, ouabain strongly potentiated histamine release elicited by compound 48/80. The full potentiation of mast cell secretion by ouabain required 30 min preincubation before adding compound 48/80. It was inhibited by lanthanum and EGTA. Potassium deprivation mimicked the effect of ouabain. A 30 min preincubation time without potassium was also required. Potassium concentrations below 2.7 mM increased the effect of ouabain whereas higher potassium concentrations reversed this effect. The potentiation of compound 48/80-induced histamine release by ouabain or potassium deprivation was not immediately reversed by washing away ouabain or by adding potassium, respectively. The data confirm that sodium-potassium ATPase is involved, through a calcium-dependent process, in the regulation of histamine release from mast cells.     

Local histamine release after immunological and non-immunological mast cell degranulation in vivo

Plasma histamine concentration in the circulation has been proposed as an index of mast cell degranulation occurring in vivo but there are problems with this approach in practice. Local elevations in plasma histamine occur in blood draining the site of antigen challenge in forearm skin. We have compared changes in plasma histamine concentration with time following intradermal injection of antigen, codeine or histamine to produce matched wheal and flare responses in 4 atopic subjects. Less histamine appears to be released after non-immunological challenge.     

Modulation of anaphylactic histamine release by calcium channel agonists and antagonists

Calcium antagonists have been reported to exert protective effects in hypersensitivity reactions in man and animals. However, their effect on anaphylactic histamine release is highly variable and controversial. In the present paper we evaluate the effect of calcium entry blockers and BAY K 8644 on the response to specific antigen in isolated hearts taken from actively sensitized guinea-pigs and from isolated rat and guinea-pig mast cells, actively or passively sensitized. Verapamil, diltiazem, nifedipine and prenylamine dose-dependently decreased anaphylactic histamine release in isolated actively sensitized guinea-pig mast cells. BAY K 8644 was found to be ineffective. In isolated, passively sensitized rat mast cells, verapamil showed a highly significant inhibitory effect, while prenylamine (10(-4) M) was able to evoke a histamine releasing effect. In cardiac anaphylaxis verapamil, diltiazem, prenylamine, but not nifedipine, were active in reducing the release of histamine without modifying the antigen-induced arrhythmias and positive chronotropic and inotropic effects.     

In vitro inhibition of allergic histamine release by calcium antagonists

The ability of calcium entry blockers to inhibit allergic histamine release from rabbit leukocytes was studied. Bepridil, verapamil, nifedipine, diltiazem and TMB-8 produced concentration-dependent inhibition of allergic histamine release from rabbit leukocytes. The calculated IC50s (microM) were as follows: verapamil = 1.3; bepridil = 2.3; TMB-8 = 3.0; nifedipine = 3.3; and diltiazem = 5.3. Verapamil also exerted concentration-dependent inhibition of allergic histamine release from human basophils with an IC50 of 3.7 microM. These agents may act by interfering with the influx of Ca2+ into the leukocytes as well as calcium-dependent steps (e.g., activation of calmodulin, phospholipase A2 and/or 5-lipoxygenase etc.) in the process of histamine secretion.     

Effect of calcium antagonists on histamine release from human basophil leukocytes

The effect of calcium antagonists on basophil activation was investigated in 14 subjects. Verapamil, methoxyverapamil and diltiazem, in a concentration range of 1-100 microM, exert a concentration-dependent inhibition on the human basophil histamine release induced by calcium ionophore A23187, zymosan activated human serum and grass pollen allergens. This inhibitory effect is highly variable from subject to subject and from drug to drug. At concentrations higher than 200 microM, verapamil, methoxyverapamil and diltiazem induce a calcium independent histamine secretion from basophil leukocytes. This mediator release is associated with an increase in LDH levels in the cell supernatant and seems to be due to a cytotoxic effect.     

Inhibition by calcium antagonists of histamine release and calcium influx of rat mast cells: Difference between induction of histamine release by concanavalin A and compound 48/80

The relation between calcium influx and histamine release from rat mast cells was investigated. When purified mast cells pretreated with a calcium antagonist (MnCl₂ or methoxyverapamil (D-600)) were exposed to concanavalin A or compound 48/80 in Tyrode solution (pH 7.4) at 37°C, the calcium antagonists inhibited the extracellular calcium-dependent component of concanavalin A-induced histamine release. MnCl₂ also inhibited the extracellular calcium-dependent component of compound 48/80-induced histamine release, whereas D-600 did not inhibit the release. D-600 inhibited the ⁴⁵Ca uptake induced by concanavalin A, but did not inhibit the ⁴⁵Ca uptake induced by compound 48/80. It was found that the inhibitory action of calcium antagonists depended on the uptake of extracellular calcium. These observations suggest that concanavalin A and compound 48/80 stimulate different mechanisms of calcium influx. Studies on inactivation of the mechanisms of calcium influx showed that calcium influx into cells activated by concavalin A stopped when concanavalin A was washed out, whereas the influxactivated by compound 48/80 was still operative after compound 48/80 had been washed out.     

Interaction between barium, strontium and calcium in histamine release by compound 48/80.

Pre-incubating rat peritoneal and pleural mast cells for 30 min at 2 degrees C in Ca2+-free Tyrode containing Ba2+ (30 mM) markedly reduced histamine release by compound 48/80 (0.5 microgram/ml). Evoked secretion was not significantly altered by pre-incubation with Sr2+ (30 mM) at this temperature whilst Mg2+ (30 mM) and La3+ (0.1 mM) slightly inhibited and potentiated release respectively. The effect of Ba2+ was concentration related and progressively reversed by Ca2+ (1--10 mM). Pre-incubation at 37 degrees C in Ca2+-free medium alone substantially reduced histamine release by compound 48/80. This reduction was unaltered by either Mg2+ (30 mM) or La3+ (0.1 mM), prevented by either Sr2+ (30 mM) or Ca2+ (1 mM) and augmented by Ba2+ (30 mM) which also markedly increased spontaneous histamine release during pre-incubation at 37 degrees C. Results suggest that Ba2+ and Sr2+ interact with cell-fixed calcium to modulate histamine release by compound 48/80.     

Effect of calcium on dextran-induced histamine release from isolated mast cells

Phosphatidyl serine potentiation of dextran-induced histamine release from isolated rat mast cells, was found to be calcium-dependent.     

Role of intracellular calcium in histamine release from rat mast cells

An aqueous extract of Panax Ginseng C.A. Meyer (G.S.) was prepared by boiling crushed G.S. roots in water. The extract obtained was adjusted to 125 mg G.S. per ml and was administered orally to mice for 5 to 6 days at the daily dose of 10, 50 and 250 mg G.S. per kg or was added to cultures of mouse spleen cells at concentrations varying between 0.25 and 8 mg G.S. per ml. The average total ginsenoside content of the G.S. roots used was determined by HPLC analysis and found to be 0.58% (w/w). Treated mice responded with enhanced antibody formation to either a primary or a secondary challenge with sheep red cells. The effects were dose-dependent. At the highest dose regimen, the primary IgM response was increased by 50% and the secondary IgG and IgM responses were increased by 50 and 100%, respectively. An even more pronounced effect was obtained with natural killer cell activity which was enhanced between 44 and 150% depending on the effector-to-target cell ratios used in the assay. In vitro, G.S. showed two main effects, an inhibition of stimulated and spontaneous lymphocyte proliferation at high, but not cytotoxic concentrations and an enhancement of interferon production particularly in non-stimulated spleen cells. The immunostimulating effects obtained in vivo are in agreement with the stimulation of interferon production observed in vitro. The inhibition of lymphocyte proliferation, however, cannot be reconciled with the immunostimulatory action of G.S. observed in vivo.     

Effects of phorbol ester, serine phospholipids, and calcium on histamine release from mast cells and basophils

The effects of calcium, serine phospholipids and the phorbol ester tetradecanoylphorbol acetate (TPA), a known activator of protein kinase C, have been examined on mastocytes from different sources. A complex and differential interaction between these agents and histamine secretion was observed in human basophil leucocytes and in peritoneal mast cells from the rat, mouse and hamster. On this basis, the possible role of kinase C in histamine release is discussed.     

Endotoxins release histamine by complement activation and potentiate bacteria-induced histamine release

The histamine-releasing capability of bacterial lipopolysaccharides (LPS) was examined in human leukocyte suspensions. LPS alone did not release histamine, but it was found to enhance the histamine release caused by bacteria in basophils from persons sensitized to these bacteria. In the presence of serum, LPS was able to release histamine through complement activation. It is speculated that endotoxins reinforce release of histamine caused by bacteria in persons sensitized to these microorganisms, and a direct mediator release via complement activation might play a role in septic conditions.     

Inhibition of immunological and non-immunological histamine release from human basophils and lung mast cells by formoterol

3-Formylamino-4-hydroxy-alpha(N-1-methyl-2-p-methoxyphenethyl-a min omethyl)benzylalcohol hemifumarate (formoterol fumarate, BD40 A, CGP 25 827 A-E) inhibited both allergic (anti-IgE) and non-allergic histamine release (calcium ionophore and human complement component C5a) from human basophils. The degree and efficacy of inhibition was comparable to that of ketotifen, equal to or better than fenoterol and ten times more potent than isoprenaline (beta 2-stimulator). Salbutamol, another beta 2-stimulator was practically ineffective in these models. Similarly the anti-IgE, calcium ionophore and complement component C5a induced release of histamine from human lung mast cells could be blocked by formoterol, its potency being again comparable to that of ketotifen. The above degranulation inhibition effect taken together with the pronounced bronchodilator property would confirm formoterol as a drug of choice in asthma with more efficient action than the other beta 2-stimulators such as fenoterol, salbutamol or isoprenaline.     

Membrane sialic acid influences basophil histamine release by interfering with calcium dependence

The influence of the cell membrane content of sialic acid on basophil histamine release was examined in vitro in allergic patients and normal controls. Enzymatical removal of sialic acid enhanced histamine release induced by allergen and anti-IgE, whereas an increase in membrane sialic acid content by insertion of sialic acid containing gangliosides into the membrane inhibited the mediator release. The reduction in membrane sialic acid content abolished the inhibitory capacity of the calcium channel antagonist nimodipine, whereas the inhibition produced by verapamil and lanthanum was not affected. This difference, together with the previous finding that alterations in membrane sialic acid content is reflected in the cell sensitivity to extracellular calcium, suggest an interaction between membrane sialic acid and the calcium channels involved in basophil histamine release.     

The inhibition by azatadine of the immunological release of leukotrienes and histamine from human lung fragments

The effects of the H1 antihistamine azatadine on the antigen-induced release of slow reacting substance of anaphylaxis (leukotrienes C4 and D4) and histamine from passively sensitized human lung fragments were determined. Azatadine 0.1-10 microM significantly and dose dependently inhibited the release of leukotrienes from lung by 22-71%. Histamine release was also inhibited by azatadine 10 microM.     

Ketotifen-induced histamine release, inhibition of histamine secretion and modulation of immune response

In concentrations above 0.1 mM Ketotifen (KT) induced secretion of histamine from rat and mouse mast cells, but not from human basophils. In the same concentrations KT inhibited histamine release from rat mast cells, induced by compound 48/80 and histamine release from basophils, induced by anti-IgE-antibodies and concanavalin A. At low concentration (0.05-0.005 mM) KT enhanced in vitro phytohemagglutinin-induced proliferative response of human lymphocytes. The immunostimulating effect of KT was confirmed in vivo. In doses 0.18-1.4 micrograms/mouse KT significantly increased the number of antibody-producing cells (APC) in spleens of mice immunized by sheep red blood cells (SRBC). KT stimulated both IgM- and IgG-immune response to SRBC.