Histamine modulates the production of interferon-gamma and interleukin-2 by mitogen-activated human mononuclear blood cells

Histamine inhibited the production of interferon-gamma and interleukin 2 (IL-2) induced in human peripheral blood mononuclear cells by Staphylococcal Enterotoxin A (SEA) but had no effect on the expression of IL-2 receptors. The effects on lymphokine production were dose dependent with maximal inhibition occurring at histamine concentrations of 10(-4) to 10(-6) M. The H2-agonist 4-methylhistamine but not the H1-agonist 2-methylhistamine modulated lymphokine production in a similar manner as histamine. Histamine at concentrations of 10(-3) to 10(-8) M had no inhibitory effect directly on the activity of admixed IL-2 containing medium. The inhibitory effects of histamine could be reversed by the H2-antagonist cimetidine but not by the H1-antagonist diphenhydramine. This indicates that the inhibitory effects of histamine on lymphokine production are mediated through H2-receptors on mononuclear cells.     

IL-8 inhibits histamine release from human basophils induced by histamine-releasing factors, connective tissue activating peptide III, and IL-3.

We have previously purified and partially characterized histamine releasing factors (HRF), which were derived from a mixture of human mononuclear cells and platelets. We now report the effect of IL-8 upon HRF-, connective tissue activating peptide III (CTAP III)-, and IL-3-induced histamine release from human basophils. We determined that IL-8 itself, at concentrations between 10(-7) to 10(-11) M, does not release histamine from basophils, although positive results are observed in two of 26 subjects at 10(-7) M. Unfractionated (crude) HRF released histamine in 25 of 26 donors, in the range of 6.7% to 100% of total basophil histamine stores. When basophils were preincubated with IL-8 (10(-7) to 10(-11) M) for 5 min, followed by a 40-min incubation with HRF, histamine release was significantly inhibited in 20 of 25 donors. Inhibition was observed at as little as 10(-11) M IL-8, with maximal inhibition being attained at 10(-9) M. HRF-containing supernatants contain a mixture of different histamine-releasing moieties. To better define which factor(s) may be inhibited by IL-8, fractionated supernatants, purified CTAP III, and IL-3 were studied. Histamine release produced by two different HRF-containing chromatographic fractions (HRFvoid and HRFpeak 2) and purified CTAP-III (5 micrograms/ml) was inhibited by IL-8 in 10 of 12 donors, three of three donors, and seven of 10 donors, respectively. IL-3 (5000 U/ml)-dependent histamine release was inhibited by IL-8 in all subjects tested. In contrast, histamine release by anti-IgE and FMLP was not affected by IL-8. Thus, IL-8 appears to be an inhibitor of cytokine-like molecules that induce histamine release and may represent the previously described 8-kDa histamine release inhibitory factor present in mononuclear cell supernatants.     

Importance of histamine in the cytokine network in the lung through H2 and H3 receptors: stimulation of IL-10 production

Histamine, a well-known inflammatory mediator, has been implicated in various immunoregulatory effects that are poorly understood. Thus, we tested the hypothesis that histamine inhibits the release of a proinflammatory cytokine, namely TNF, by stimulating the release of an anti-inflammatory cytokine, IL-10. Alveolar macrophages (AMs) from humans, Sprague Dawley rats, and the AM cell line, NR8383, were treated with different concentrations of histamine (10-5-10-7 M) for 2 h prior to their stimulation with suboptimal concentration of LPS (1 ng/ml) for 4 h. Histamine inhibited TNF release in a dose-dependent manner. This inhibition was mimicked by H2 and H3 receptor agonists, but not by H1 receptor agonist. Furthermore, we demonstrated the expression of H3 receptor mRNA in human AMs. Interestingly, treatment of AMs with anti-IL-10, anti-PGE2, or a NO synthase inhibitor (Nomega-nitro-l -arginine methyl ester) before the addition of histamine abrogated the inhibitory effect of the latter on TNF release. Histamine treatment (10-5 M) increased the release of IL-10 from unstimulated (2.2-fold) and LPS-stimulated (1. 7-fold) AMs. Unstimulated AMs, NR8383, express few copies of IL-10 mRNA, as tested by quantitative PCR, but expression of IL-10 was increased by 1.5-fold with histamine treatment. Moreover, the stimulation of IL-10 release by histamine was abrogated by pretreatment with anti-PGE2 or the NO synthase inhibitor, Nomega-nitro-l -arginine methyl ester. Thus, histamine increases the synthesis and release of IL-10 from AMs through PGE2 and NO production. These results suggest that histamine may play an important role in the modulation of the cytokine network.     

Histamine is a potent inducer of IL-18 and IFN-gamma in human peripheral blood mononuclear cells

Histamine (10-7 to 10-4 M) concentration-dependently stimulated the production of IL-18 and IFN-gamma and inhibited the production of IL-2 and IL-10 in human PBMCs. Histamine in the same concentration range did not induce the production of IL-12 at all. The stimulatory or inhibitory effects of histamine on cytokine production were all antagonized by H2 receptor antagonists ranitidine and famotidine in a concentration-dependent manner, but not by H1 and H3 receptor antagonists. Selective H2 receptor agonists, 4-methylhistamine and dimaprit, mimicked the effects of histamine on five kinds of cytokine production. The EC50 values of histamine, 4-methylhistamine, and dimaprit for the production of IL-18 were 1.5, 1.0, and 3.8 microM, respectively. These findings indicated that histamine caused cytokine responses through the stimulation of H2 receptors. All effects of histamine on cytokine responses were also abolished by the presence of either anti-IL-18 Ab or IL-1beta-converting enzyme/caspase-1 inhibitor, indicating that the histamine action is dependent on mature IL-18 secretion and that IL-18 production is located upstream of the cytokine cascade activated by histamine. The addition of recombinant human IL-18 to the culture concentration-dependently stimulated IL-12 and IFN-gamma production and inhibited the IL-2 and IL-10 production. IFN-gamma production induced by IL-18 was inhibited by anti-IL-12 Ab, showing the marked contrast of the effect of histamine. Thus histamine is a very important modulator of Th1 cytokine production in PBMCs and is quite unique in triggering IL-18-initiating cytokine cascade without inducing IL-12 production.     

Histamine-induced inositol phosphate accumulation in type-2 astrocytes

Histamine elicited dose-dependent accumulation of [3H]inositol phosphates in type-2 astrocytes, but not in type-1 astrocytes. The ED50 was about 2.4 x 10(-6) M and the maximal response was obtained at 10(-4) M. This response was dose-dependently inhibited by H1-antagonists, mepyramine and D- and L-chlorpheniramine. Furthermore, D- and L-chlorpheniramine showed stereoselectivity in the inhibition. On the other hand, an H2-antagonist, famotidine, and an H3-antagonist, thioperamide, did not inhibit the response. These results indicate that histamine stimulates accumulation of inositol phosphates in type-2 astrocytes via H1-receptors.     

Autoregulation of enterochromaffin-like cell histamine secretion via the histamine 3 receptor subtype.

INTRODUCTION: The neuroendocrine histamine-secreting cell of the gastric fundus, the enferochromaffin-like cell, is the principal regulator of parietal cell acid secretion. We have proposed that histamine may regulate its own synthesis and release via an autocrine mechanism. The purpose of this study was to evaluate the role of the histamine receptor subtypes H1, H2 and H3 in the regulation of this phenomenon. METHODS: Purified ECL cells were isolated by pronase digestion and EDTA exposure of the rat stomach, followed by particle size and density separation using counterflow elutriation and Nycodenz gradient centrifugation, 24-hr cultured cells were pretreated for 30 min with the agents; H1 receptor agonist (2-[(3-trimethyl)-diphenyl] histamine) (TMPH), H1 receptor antagonist (terfenadine); H2 receptor agonist (dimaprit) or antagonist (cimetidine or loxitidine); or H3 receptor agonist (imetit) or antagonist (thioperamide) (all tested, 10(-10)-10(-6) M). Gastrin was then used to stimulate histamine secretion. Histamine secretion was quantified by specific enzyme-immunoassay. RESULTS: Basal histamine secretion was 2.7 +/- 0.14 nmol/10(3) cells. Gastrin-stimulated (10 nM) levels were 4.6 +/- 0.4 nmol/10(3) cells (p < .01). TMPH inhibited both basal and gastrin driven histamine secretion with a maximal effect (34 percent) (1.78 +/- 0.08 nmol/10(3) cells) and an IC50 of > 5 x 10(-7) M. H1 receptor antagonism did not alter histamine secretion alone or in combination with gastrin. Neither H2 receptor stimulation nor antagonism had any effect on histamine secretion alone or in combination with gastrin. Gastrin-induced histamine secretion was dose-dependently inhibited by imetit (H3 agonist) with a maximal effect (2.4 +/- 0.6 nmol/10(3) cells) (p < .05) and an IC50 of 10(-9) M. Conversely, Thioperamide (H3 antagonist) dose-dependently augmented gastrin-stimulated histamine secretion with a maximum effect (5.7 +/- 0.5 nmol/10(3) cells) (p < .05) at 10(-8) M and an EC50 of 7 x 10(-10) M. CONCLUSION: These data are consistent with the presence of an H3 receptor on the ECL cell which modulates gastrin-stimulated histamine secretion. Our observations support the proposal that a histamine-mediated short-loop autocrine regulatory mechanism of ECL cell secretion exists.     

Survival of human macrophages infected with Mycobacterium avium intracellulare correlates with increased production of tumor necrosis factor-alpha and IL-6

The long term survival of peripheral blood derived human macrophages (M phi) from normal, healthy donors after infection with Mycobacterium avium intracellulare (MAI) correlates with the increased induction of TNF-alpha and IL-6 mRNA and protein by the infected M phi. This conclusion is based on the following observations: M phi from approximately 30% of the blood donors in our study die 3 to 4 days after inoculation (MAI-growth nonsupportive (NS], whereas M phi from the other donors survive inoculation with MAI for 7-10 days (MAI-growth supportive (S)). S-type M phi when infected with MAI had markedly increased amounts of TNF-alpha and IL-6 mRNA and protein when compared to NS-type M phi. The effect of LPS on the induction of TNF-alpha mRNA and protein was also significantly enhanced in S-type M phi in comparison to NS cells. In contrast, IL-1 beta mRNA and protein production had similar increases in both donor types when infected with MAI or stimulated with LPS. The phenotype of the donors in the amount of TNF-alpha and IL-6 produced in response to MAI infection remained stable for a period of more than 1 yr. Pretreatment of NS M phi with recombinant human granulocyte-macrophage-CSF, but not IFN-gamma, however, converted NS M phi into a S-type cell phenotype. These granulocyte-macrophage-CSF pretreated NS M phi survived infection with MAI for a longer period of time and also had increased production of both TNF-alpha and IL-6 mRNA and protein. Cultures of S-type M phi infected with MAI had higher numbers of intracellular bacteria when compared to cultures of NS-infected M phi. Thus, increased survival of MAI-infected human M phi in vitro is correlated to increased production of TNF-alpha and IL-6 in response to infection with MAI.     

Comparative effect of recombinant IL-1, -2, -3, -4, and -6, IFN-gamma, granulocyte-macrophage-colony-stimulating factor, tumor necrosis factor-alpha, and histamine-releasing factors on the secretion of histamine from basophils

Most cytokines possess multiple biologic activities. This study was undertaken to investigate the effect of rIL-1 beta, -2, -3, -4 and -6, IFN-gamma, TNF-alpha, and granulocyte-macrophage (GM)-CSF on basophils from 16 donors and the amount of histamine released was compared with that by partially purified mononuclear cell-derived histamine-releasing factor (HRF) and anti-IgE. We found that only IL-3 and GM-CSF at relatively high doses (50 to 500 ng/ml) released small amounts of histamine (3 to 14%) from two allergic donors. In contrast, both HRF and anti-IgE released significant amounts of histamine from all donors. Other cytokines did not release any measurable quantity of histamine. Simultaneous addition of several cytokines to the basophils also failed to release histamine. IL-3, GM-CSF, and IL-1 can also release histamine at lower concentrations (less than 5 ng/ml) when incubated with basophils in the presence of D2O. Basophils from 6 out of 13 allergic donors released histamine in response to IL-3, whereas three donors responded to IL-1 beta and two responded to GM-CSF. The results of this study demonstrated that although IL-3 and GM-CSF release small amounts of histamine only from a select group of allergic patients, mononuclear cell-derived HRF is more potent in their action and release histamine from normals as well as allergic patients.     

Effect of hydrocortisone on interleukin-6 production in human ,peripheral blood rnononuclear ceils

The effect of hydrocortisone on the production of interleukin-6 (IL-6) in human peripheral blood mononuclear cells was studied. Using our newly developed radioimmunoassay system for IL-6 of which specificity, reproducibility, sensitivity and usefulness have been demonstrated. IL-6 production in peripheral blood mononuclear cells of ten normal subjects revealed that in lipopolysaccharide (LPS, 10mug/ml)-stimulation, the mean +/- SD of IL-6 was 2.71 +/- 0.85 ng/ml. No detectable amount of IL-6 was observed in the absence of LPS and in the presence of hydrocortisone alone. Hydrocortisone (10(-10) M to 10(-3) M) inhibited LPS-stimulated IL-6 production in a dose-dependent manner. However, there was a wide variation in the response to hydrocortisone, namely, ranging from steroid-sensitive to steroid-resistant. Based on the concentration required to inhibit 50% of LPS-stimulated IL-6 production, three of ten subjects were at 10(-6) M, three at 10(-5) M and the rest at 10(-4) M, respectively. The dramatic anti-inflammatory and immunosuppressive effects of glucocorticosteroids can be life-saving in autoimmune diseases. The present findings suggested that there existed the differences in susceptibility to glucocorticosteroids even among normal subjects, providing some implications for the drug treatment, and also gave further evidence that there may exist an immunoregulatory feedback circuit between the immune and neuroendocrine systems.     

Differential inhibition of IL-1 and TNF-alpha mRNA expression by agents which block second messenger pathways in murine macrophages

IL-1 and TNF-alpha are induced in macrophages by LPS; however, it is unclear whether similar mechanisms control the expression of both genes. Here, we report on the detection of differential regulation of LPS induced IL-1 and TNF-alpha mRNA expression and protein production in murine macrophages based on the use of inhibitors of second messenger pathways. Northern blot analysis was performed with total RNA obtained from murine (C57Bl/6) peritoneal macrophages stimulated in vitro with LPS with or without an inhibitor of protein kinase C (PKc)(1-(5-isoquinolinesulfonyl)-2-methylpiperazine hydrochloride; H7) or an inhibitor of calmodulin (CaM)-dependent kinase (N-(6-amino-hexyl)-5-chloro-1-naphthalene-sulfonamide hydrochloride; W7). Northerns were analyzed with probes for IL-1 alpha and IL-1 beta and TNF-alpha. The expression of the three cytokine mRNA by LPS was inhibited in a dose response manner by H7. In contrast, the expression of IL-1 mRNA, but not TNF-alpha mRNA, was blocked by treatment with W7. Parallel studies monitoring biologic activities of these two cytokines confirm the mRNA data. PKc inhibitors, H7 and retinal, block both IL-1 and TNF-alpha protein production and inhibitors of CaM kinase, W7, N-(6-aminobutyl)-5-chloro-2-naphthalenesulfonamide, calmidazolum, and trifluoperazine dichloride inhibit only IL-1 production. These data suggest that both PKc and CaM kinase dependent pathways are involved in the induction of IL-1 mRNA by LPS. In contrast, TNF-alpha expression appears to be PKc dependent but not CaM kinase dependent.     

Suppression of pulmonary and systemic vascular histamine H2-receptors in allergic sheep

We have previously demonstrated a depression of airway H2-receptor function in sheep allergic to Ascaris suum antigen. To investigate whether this is a generalized defect, we studied the H1- and H2- histamine receptor functions in the pulmonary and systemic circulations of allergic and nonallergic sheep. Pulmonary arterial pressure, and cardiac output were measured for calculation of pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) before and immediately after a rapid intrapulmonary infusion of histamine (10 micrograms/kg), with and without pretreatment with H1- (chlorpheniramine) and H2- (metiamide) antagonists. Histamine alone increased mean PVR to 435 and 401% of base line and decreased mean SVR by 51 and 54% in the nonallergic and allergic sheep, respectively (P less than 0.001). In the nonallergic sheep following pretreatment with chlorpheniramine (selective H2 stimulation) or metiamide (selective H1 stimulation), histamine decreased SVR by 18 and 36%, respectively, suggesting that approximately two-thirds of the vasodepressor response was mediated by H1-receptors and one-third by H2-receptors. Combined H1- and H2-antagonists completely blocked the histamine response. In allergic sheep the histamine-induced decrease in SVR was primarily mediated by H1-receptors, because the response was blocked by H1-antagonist, chlorpheniramine, and the H2-antagonist, metiamide, had no effect. In the pulmonary circulation selective H1-stimulation caused a similar increase in PVR in allergic (365%) and nonallergic sheep (424%), whereas selective H2-stimulation caused a significant decrease in PVR in the nonallergic group (14%) but not in the allergic group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Serotonin-induced stimulation of progesterone production by cow luteal cells in vitro

The addition of acetylcholine or histamine (10(-7) to 10(-4) M), gamma-aminobutyric acid, a dopamine agonist, and melatonin (10(-7) to 10(-5) M) did not alter basal or LH-stimulated progesterone production (P greater than 0.05). The addition of the specific beta 2-adrenergic agonist terbutaline and salbutamol did not significantly elevate progesterone production. Treatment of luteal cells with serotonin (5-HT), 10(-6) to 10(-4) M, increased the production of progesterone (P less than 0.05). This stimulated production was inhibited by the addition of mianserin (10(-5) M, a 5-HT antagonist; P less than 0.05). Isoproterenol (10(-7) to 10(-4) M) also resulted in significant increases in progesterone production (P less than 0.05). The combined treatments of 5-HT + LH, isoproterenol + LH, or isoproterenol + 5-HT did not result in a further increase in progesterone above that observed in response to LH or isoproterenol alone (P greater than 0.05). The isoproterenol-induced progesterone production could not be blocked by butoxamine (10(-5) M, a beta 2-antagonist), or practolol (10(-5) M, a beta 1-antagonist), but was inhibited by propranolol (10(-5) M, a general beta-antagonist; P less than 0.05). The response to isoproterenol was unaffected by mianserin (10(-5) M). These results demonstrate a possible role for 5-HT in the regulation of steroidogenesis by the corpus luteum of the cow. Furthermore, these results suggest that serotonin-induced progesterone production is a receptor-mediated event.     

Calcium ionophore (A23187) increases interleukin 1 (IL-1) production by human peripheral blood monocytes and interacts synergistically with IL-1 to augment concanavalin A stimulated thymocyte proliferation

The effects of calcium ionophore, A23187, on production of interleukin 1 (IL-1) by human peripheral blood monocytes (PEMo) and on murine thymocyte proliferation were examined. A23187 induced IL-1 production by human PBMo. The optimal dose was 10(-6) M. Although IL-1 production induced by A23187 was less than that by lipopolysaccharide (LPS) or silica, A23187 together with LPS had a synergistic effect on induction of IL-1. A23187 also had a more marked synergistic effect in concert with Concanavalin A and/or IL-1 on murine thymocyte proliferation. The optimal dose was also 10(-6) M. This represents the first report suggesting that monocytes or the monocyte product, IL-1, may contribute to the mitogenic effect of A23187 for thymocytes.     

Neisseria meningitidis can induce pro-inflammatory cytokine production via pathways independent from CD14 and toll-like receptor 4

Fulminant meningococcal sepsis (FMS) is considered the prototypical Gram-negative sepsis. Lipopolysaccharide (LPS) is thought to be the main toxic element that induces pro-inflammatory cytokine production after interaction with CD14 and toll-like receptor 4 (TLR4). However, there is increasing evidence that LPS is not the sole toxic element of meningococci. The aim of the present study was to determine the role of CD14 and TLR4 in pro-inflammatory cytokine induction by meningococci. To this end, cytokine induction by isolated meningoccal LPS, wild-type N. meningitidis H44/76 (LPS+-meningococci) matched for concentrations of LPS and LPS-deficient N. meningitidis H44/76lpxA (LPS - -meningococci) was studied in human PBMCs and murine peritoneal macrophages (PMs). Pre-incubation of PBMCs with WT14, a monoclonal antibody against CD14, abolished TNF-alpha and IL-1beta induction by E. coli LPS, while cytokine induction by meningococcal LPS was only partially inhibited. When LPS+- and LPS - -meningococci at higher concentrations were used as stimuli, anti-CD14 had a minimal effect. In C3H/HeJ murine PMs, devoid of a functional TLR4, minimal IL-1alpha, IL-6 and TNF-alpha production was seen after stimulation with 10 ng/mL E. coli or meningococcal LPS. However, at higher concentrations (1000 ng LPS/mL) the production of TNF-alpha, but not IL-1alpha or IL-6, occurred also independently of TLR4. The expression of a functional TLR4 in murine PMs had no effect on the cytokine induction by LPS+- or LPS - -meningococci. It is concluded that pro-inflammatory cytokine induction by N. meningitidis can occur independently of CD14 and TLR4.     

Histamine receptor effects on dissipation of an intracellular proton gradient of isolated gastric mucosal surface cells

The effects of histamine and several H1 and H2 receptor agents on Na+/H+ and Cl-/HCO-3 exchange systems of isolated gastric mucosal surface cells were studied. The cells were acid-loaded by the NH4Cl prepulse technique and the spontaneous Na+- and HCO-3-induced dissipation of the intracellular proton gradient (pHi) was followed using the metachromatic dye acridine orange. Histamine (10(-2-5) M) stimulates HCO-3-induced dissipation of the pHi but has no effect on Na+-induced or spontaneous dissipation. The H1 agonist 2-(2-aminoethyl)pyridine and the H2 agonist dimaprit also have no effect on Na+-induced or spontaneous pHi dissipation. However, both of these agents mimic the effect of histamine on HCO-3-induced dissipation, but only at a higher concentration (10(-3) M). The combination of 2-(2-aminoethyl)pyridine and dimaprit produces a histamine-like effect at lower concentrations (10(-5) and 10(-4) M). The effects of histamine are blocked by either the H1 antagonists diphenhydramine and pyrilamine or the H2 antagonists cimetidine and SKF 93479. The results suggest that the effect of histamine on HCO-3-induced dissipation of a pHi in gastric mucosal surface cells is mediated through a coordinated mechanism involving both H1 and H2 receptor sites.     

Effects of histamine on contractile activity of lymphatic node capsules. The NO role

Effects of histamine (10(-9)--5 x 10(-5) M) on the phase and tonic contractile activity of capsular smooth muscles of isolated bovine mesentery lymph node were investigated. Dual dose-depended effect of histamine was found. Low concentrations of histamine less than 10(-7) M caused a decrease of contractile activity, whereas higher concentrations of histamine (more than 5 x 10(-7) M) resulted in increase of the phase and tonic contractions. Both H1- and H2-receptors of smooth muscle cells are involved in the response. Much of the relaxing histamine-induced response is produced by the stimulation of the endothelial cells. We believe that activating effect of histamine is due to the excitation of H1-receptors located on the membrane of myocytes, whereas its inhibitory effect occurs in two ways: 1) via excitation of H2-receptors located on the membrane of myocytes; 2) via stimulation of the NO production by the endothelial cells of lymph node sinus.     

The influence of histamine on precursors of granulocytic leukocytes in murine bone marrow

The effect of histamine on granulocytic progenitor cells in murine bone marrow was studied in vitro. When bone marrow cells were cultured for three days with the drug, 10(-8) M to 10(-5) M of histamine stimulated differentiation and proliferation of myeloid precursor cells. Subsequently, the number of descendant cells, such as metamyelocytes and neutrophils, increased dose-dependently. Co-existence of equimolar H2 blockers such as cimetidine and ranitidine completely suppressed this effect of histamine, though this was not the case with an H1 blocker/histamine combination. Significant increase in 3H-thymidine incorporation was observed almost exclusively in myeloblasts, promyelocytes and myelocytes after exposure to histamine at concentrations higher than 10(-8) M. Also, selective incorporation of 3H-histamine into bone marrow cells was observed in myeloblasts and promyelocytes, but histamine incorporation was not influenced by the presence of either of histamine agonists or antagonists. While histamine, via H2 receptors, selectively increased the number of granulocytic colony forming units in culture (CFU-C), it had no such effect on macrophage colonies. Considering these findings, it was concluded that histamine promotes proliferation and differentiation of granulocytic myeloid cells via 1) H2 receptors in the CFU-C stage and 2) histamine receptors which are neither H1 nor H2 in the stages of myeloblast and promyelocyte differentiation.     

Mast cell mediators prostaglandin-D2 and histamine activate human eosinophils.

Airway damage secondary to eosinophil activation is thought to contribute to the development of asthma. Using the fluorescent dye FURA-2 to measure the concentration of cytosolic calcium, we found that supernatants from anti-IgE-stimulated human lung mast cells increased cytosolic calcium in human eosinophils. We then examined the major mast cell mediators (histamine, PGD2, platelet-activating factor (PAF), eosinophil chemotactic factor of anaphylaxis (ECF-A), leukotriene (LT)C4 and LTB4) for their ability to increase cytosolic calcium in eosinophils. We found that both PAF (5 x 10(-9) to 5 x 10(-6) M) and PGD2 (two of five donors responsive at 1 x 10(-9) M) were potent stimuli for calcium mobilization. LTB4 (10(-8), 10(-7) M) and histamine were also active, although higher concentrations of histamine were required to see a response (3 x 10(-7) to 10(-5) M). LTC4, val-ECF-A, and ala-ECF-A were inactive. The effects of PGD2 and histamine were specific for eosinophils, although LTB4 and PAF increased calcium in both neutrophils and eosinophils. The histamine-induced increase in intracellular calcium was not blocked by the H1 or H2 antagonists pyrilamine or cimetidine (10(-4) M), respectively; however, the response to 10(-6) M histamine was completely blocked by the specific H3 antagonist thioperamide (10(-6) M). To evaluate the relative contribution of these stimulatory mast cell mediators on the calcium mobilizing activity in supernatants from anti-IgE-stimulated human lung mast cell (HLMC), we examined the effect of supernatants from HLMC pretreated with indomethacin and/or the 5-lipoxygenase pathway inhibitor MK886. These supernatants were added to FURA-2-loaded eosinophils that had been preincubated with thioperamide and/or the PAF antagonist WEB-2086. We found that the increase in eosinophil calcium in response to supernatants from anti-IgE-stimulated-HLMC was totally inhibited only when the mast cells were challenged in the presence of indomethacin and MK886, and the eosinophils were preincubated with thioperamide. WEB-2086 had little effect. When we examined the effect of these mediators on eosinophil secretory function, we found that PGD2 (not histamine) primed eosinophils for enhanced release of LTC4 in response to the calcium ionophore A23187. We conclude that the activation of eosinophils by PGD2 and other mast cell products may contribute to airways inflammation that is characteristic of asthma.     

Complement- and IgE-mediated release of histamine from basophils in vitro. V. Differential effects of drugs modulating arachidonic acid metabolism

Basophil degranulation probably plays a significant role in the pathogenesis of different hypersensitivity reactions. These cells can be stimulated to secrete lysosomal histamine in vitro in response to various secretagogues. We compared the effects of drugs, modulating arachidonic acid (AA) metabolism, on histamine release (HR) from human basophils stimulated by anti-IgE antibody or C5a anaphylatoxin. Leukocytes from normal donors were preincubated with drug for 15 min at 22 degrees C, followed by the addition of C5a or anti-IgE for 30 min at 37 degrees C. Bromophenacyl bromide, an inhibitor of AA formation by phospholipase, blocked the effects of C5a and anti-IgE (greater than or equal to 3.3 X 10(-6) M, p less than 0.05 and p less than 0.01, respectively). 3-Amino-1-(3-trifluoromethylphenyl)-2-pyrazoline hydrochloride (BW755C, greater than or equal to 3.3 X 10(-5) M) and 5, 8, 11, 14-eicosatetraynoic acid (greater than or equal to 3.3 X 10(-4) M), known inhibitors of both cyclooxygenase (COX) and lipoxygenase (LPX) pathways of AA metabolism, blocked both C5a- and anti-IgE-induced HR (p less than 0.01). Nordihydroguaiaretic acid, an inhibitor of LPX, decreased HR induced by anti-IgE (greater than or equal to 3.3 X 10(-6) M, p less than 0.01) and allergens, but reduced C5a-initiated HR only at a higher concentration (greater than or equal to 7 X 10(-5) M, p less than 0.01). Indomethacin (INDO), an inhibitor of COX, significantly reduced HR caused by C5a (greater than or equal to 3.3 X 10(-8) M, p less than 0.01) and its degradation product C5adesArg, but had no effect or caused slight enhancement of HR initiated by anti-IgE. We confirmed that INDO augments allergen-induced HR. Our findings suggest that there are basic differences in the regulation of C5a- and IgE-mediated basophil degranulation.     

Regulation of IL-1beta and IL-8 production by mu-, delta-opiate receptors agonists in vitro

The beta-endorphin 10(-7-)-10(-11) M in LPS (lypopolisaccharide) presence and in spontaneous cultures promoted the IL-1beta production in mixed leukocyte fraction. LPS-induced IL-8 production in leukocyte fraction was inhibited by beta-endorphin 10(-7), 10(-11) M. The enchasing effect of beta-endorphin on IL-1beta production was not blocked by naloxone and naltrindole. The inhibitory effect of beta-endorphin on IL-8 production was blocked by naloxone and naltrindole. In mononuclear and neutrophile fractions beta-endorphin and delta-agonist DADLE enchased IL-1beta production in spontaneous and LPS-stimulating cultures, when IL-8 production inhibited beta-endorphin and delta-agonist DADLE only in LPS presence. No effect of mu-agonist DAGO were observed on IL-1beta production, whereas LPS-induced IL-8 secretion in neutrophile fraction inhibited by DAGO.