Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BASOPHILS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed2003

Flow cytometry versus histamine release analysis of in vitro basophil degranulation in allergy to Hymenoptera venom.

BACKGROUND: Flow cytometry (FCM) has been proposed for specific allergy in vitro testing. We investigated its biological significance for allergy to Hymenoptera venoms and compared it with the routinely performed basophil histamine release test (HRT). METHODS: Blood samples from 26 allergic and 8 nonallergic donors were incubated with venom at serial concentrations. Basophils were analyzed with anti-CD45-PE-Cyanin 5, Anti-IgE-FITC, and Anti-CD63-Phycoerythrine. HRT was measured by radioimmunoassay. RESULTS: FCM was as convenient as HRT for measuring basophil reactivity in at least 87% of allergic and 75% of nonallergic subjects. CD63 outer expression was specifically induced in 91% of releaser subjects (86% on HRT) and in 1 of 10 tests in nonallergic donors, or one of six tests (16% on HRT) in allergic patients tested with an irrelevant allergen. Both methods were concordant in 85.7% of the tests. The three discordant patients had low-grade reactions and borderline biological responses on FCM (n = 2) or HRT (n = 1). CONCLUSIONS: The dynamic, physiologic significance of CD63, the dose-response curve, and dependency on ethylene-diaminetetra acetic acid suggested that both tests reflect the same mechanism.

Adolescent↗
PubMed2007

Flow-assisted quantification of in vitro activated basophils in the diagnosis of wasp venom allergy and follow-up of wasp venom immunotherapy.

BACKGROUND: Correct identification of the culprit venom is a prerequisite for specific venom immunotherapy (VIT). Despite the efficacy of VIT, issues as how to monitor treatment and when to discontinue maintenance therapy remain to be established. METHODS: To evaluate diagnostic performances of the basophil activation test (BAT) in wasp venom allergy, 80 patients with a definite history of wasp venom anaphylaxis (systemic reactors) and 14 wasp-stung asymptomatic controls (stung controls) were enrolled. Venom-induced basophil activation was analyzed flow cytometrically by double-labeling with anti-IgE and anti-CD63. Results were compared to wasp IgE levels and results of a venom skin test (VST). To establish whether the BAT constitutes a candidate marker to monitor VIT, the BAT was repeated in 22 patients on the 5th day of a build-up course and after 6 months of maintenance VIT. Whether the BAT could contribute in the decision of discontinuing VIT was assessed in a cross-sectional analysis in 30 patients receiving treatment for 3 years. RESULTS: Comparison between systemic reactors and stung controls revealed a sensitivity of 86.4% and specificity of 100% for venom IgE, and sensitivity of 81.8% for VST, respectively. In contrast to stung controls, patients demonstrated dose-dependent venom-induced basophil activation. The BAT attained a sensitivity of 83.8% and specificity of 100%. At the end of the build-up course, no effect of VIT on the BAT was demonstrable. When the BAT was repeated after 6 months of treatment, submaximal stimulation of the cells demonstrated a significant decreased CD63 expression (P < 0.04). Patients having VIT for 3 years also demonstrated significantly lower venom-induced CD63 expression (P < 0.001). After 3 years, 60% of the patients had a negative BAT for submaximal stimulation of the cells whereas only 17.9% of the patients had negativation of wasp IgE. CONCLUSIONS: The BAT is a reliable instrument for the diagnosis of wasp venom anaphylaxis and might constitute an instrument to monitor wasp VIT.

Adolescent↗
PubMed1990

Reactivity of human basophils to anti-IgE and protein A in atopic dermatitis.

We compared by basophil degranulation and histamine release the reactivity to protein A and anti-IgE of the basophils from 3 groups of patients: group I (blood donors), group II (rhinitis) and group III (atopic dermatitis). We demonstrated that histamine release and basophil degranulation gave tightly correlated results and that by both methods group III was significantly (p less than 0.01) more sensitive to the effectors than the two other groups. Protein A and anti-IgE stimulation curves showed a rebound effect at low concentrations of effectors. This was, however, only significant (p less than 0.01) for group III. Bacterial hypersensitivity may be IgE-mediated and may be related to the increased sensitivity to bacterial antigens and the severity of atopic dermatitis in patients infected by Staphylococcus aureus.

Basophil Degranulation Test↗
PubMed2001

Differential mediator release from basophils of allergic and non-allergic asthmatic patients after stimulation with anti-IgE and C5a.

The differentiation between allergic and non-allergic asthma is a common and important challenge for the clinician. Until now, no in vitro diagnostic characteristics have been described to distinguish between these types. To examine the diagnostic value of a basophil stimulation test, we compared anti-IgE- and C5a-induced mediator release from peripheral blood leucocytes in different types of bronchial asthma. Peripheral blood leucocytes (PBL) from 10 aspirin-sensitive asthmatics (ASA), 12 non-allergic asthmatics without aspirin intolerance (NAA), seven allergic asthmatics (AA), and nine healthy controls were prepared by dextran sedimentation. After priming with interleukin-3 (IL-3) PBL were stimulated with anti-IgE and C5a, and the release of histamine (HR) and sulfidoleukotrienes (LTR) in the supernatant was compared. Additionally, purified leucocyte fractions were studied to determine the cellular source of mediator release. Upon stimulation with anti-IgE LTR was slightly, but not significantly, lower in ASA and NAA compared to AA and controls. In contrast, C5a-triggered LTR was significantly higher in ASA (14.4 +/- 12.88 pg/105 cells) and NAA (22.9 +/- 22.61 pg/105 cells) than in AA (9.6 +/- 3.29 pg/105 cells) and controls (7.5 +/- 7.19 pg/105 cells) (P < 0.05). This difference between ASA and NAA vs. AA and controls was even more pronounced when determining the quotient C5a-/anti-IgE-induced LTR (P < 0.001). At an optimal cut-off point of 1.0, calculated by relative operating characteristics (ROC) analysis, the positive predictive value for a donor to belong to ASA or NAA was 0.94. No significant differences could be found in HR between the asthmatic patient groups and healthy controls in either condition. As cellular source of LTR and HR the basophil could be determined. Determination of anti-IgE- and C5a-induced LTR from basophils allows us to discriminate between allergic and non-allergic asthmatic patients. For diagnostic purposes the quotient C5a-/anti-IgE-induced LTR is more significant than considering a single parameter. ASA cannot be distinguished from NAA.

Adolescent↗
PubMed1965

FORMATION OF CHARCOT-LEYDEN CRYSTALS IN HUMAN EOSINOPHILS AND BASOPHILS AND STUDY OF THE COMPOSITION OF ISOLATED CRYSTALS.

Methods are described for the isolation of human eosinophils and basophils from donor blood. Using these cell preparations Charcot-Leyden crystals were found to originate from both eosinophils and basophils when the cells were suspended in hypotonic saline solution. The crystals formed also when saline extracts of eosinophils and basophils were concentrated by ultrafiltration through dialysis tubing. Fractions of eosinophils were prepared and the crystals were obtained from the cytoplasmic fraction but not from the nuclear or granular fractions. Chemical studies showed the crystals to be protein in nature and some evidence is presented which suggests that RNA may decrease the tendency for the protein to crystallize out of solution.

Basophils↗
PubMed2004

Requirement of the tyrosines at residues 258 and 270 of MAIR-I in inhibitory effect on degranulation from basophilic leukemia RBL-2H3.

Mast cells and basophils express the high affinity receptor for IgE (FcepsilonRI) and play a central role for IgE-associated immediate hypersensitivity reactions and allergic disorders. Cross-linking of FcepsilonRI-bound IgE with multivalent antigen initiates the activation of mast cells and basophils, resulting in the degranulation from these cells. We have recently identified a novel inhibitory receptor, myeloid-associated immunoglobulin-like receptor (MAIR)-I, which is expressed on mast cells as well as other myeloid cell lineages. Co-ligation of FcepsilonRI and MAIR-I inhibits IgE-mediated degranulation from mast cells. However, MAIR-I-mediated signaling pathways involved in the inhibition remain undetermined. Here, we demonstrate that the transfectant of rat basophil leukemia RBL-2H3 expressing wild-type MAIR-I is tyrosine phosphorylated and recruits SHP-1 and SHIP upon cross-linking of MAIR-I. By using RBL-2H3 transfectants expressing variable mutant MAIR-I at Y233, Y258, Y270 and/or Y299, we further demonstrate that both Y258 and Y270, but not Y233 and Y299, were phosphorylated and were essentially required for inhibition of IgE-mediated degranulation from the RBL-2H3 transfectant.

Amino Acid Substitution↗
PubMed2004

The flow-cytometric determination of basophil activation induced by aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) is useful for in vitro diagnosis of the NSAID hypersensitivity syndrome.

BACKGROUND: Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs), manifested by cutaneous symptoms and/or airway manifestations represent 20-25% of all hypersensitivity reactions to drugs. Today, it is still claimed that no in vitro diagnostic tests exist for that condition and that the only way to confirm the diagnosis is a provocation challenge. OBJECTIVE: The objective of this study was to assess whether NSAIDs may provoke blood basophil activation in vitro in such patients, as detected by a flowcytometric technique. METHODS: Sixty NSAID hypersensitive patients (38 with cutaneous, 20 with airway and two with cutaneous and airway symptoms) and 30 control patients (15 asthmatics) were selected. Their hypersensitivity was confirmed by documented history indicating at least two clinical episodes to two or more different NSAIDs or by positive oral provocation challenge. Isolated buffy coat leukocytes were stimulated in vitro with aspirin, paracetamol, metamizol, diclofenac, and naproxen. The percentage of activated basophils was evaluated by an anti-CD63. RESULTS: Aspirin showed a sensitivity of 43.3%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%. For the other NSAIDs, the sensitivity and specificity values were: for paracetamol 11.7% and 100%, for metamizol 15% and 100%, for diclofenac 43.3% and 93.3% and for naproxen 54.8% and 74.1%. When considering the first four NSAIDs, the global sensitivity raised to 63.3% and specificity to 93.3%. If the number of tests is to be limited for practical reasons, the combination of acetylsalicylic acid and diclofenac at two concentrations yields a sensitivity of 58.3% and a specificity of 93.3%. CONCLUSIONS: Flowcytometric determinations of basophil activation following stimulation with NSAIDs show a high sensitivity (60-70%) with specificity above 90%. So this test may help avoiding some cumbersome and dangerous provocation challenges.

Acetaminophen↗
PubMed1991

An unusual form of chronic myeloproliferative disorder. Aleukemic basophilic leukemia.

A 52-year-old Japanese man manifested various clinical signs and symptoms such as vomiting, high fever, dyspnea, cough, sweating, palpitation, eosinophilic leukocytosis and hepatosplenomegaly. These histamine-related clinical manifestations showed a dramatic response to steroid therapy. After 10 months of hospitalization, he suddenly succumbed to candidal septicemia at the end of the third cycle of steroid therapy. Autopsy revealed neoplastic proliferation of immature basophils in various internal organs without involvement of the skin. The neoplastic cells, positive immunohistochemically for leukocyte common antigen, possessed lobulated nuclei and weakly metachromatic cytoplasmic granules, predominantly of the basophil type, which exhibited weak naphthol ASD-chloroacetate esterase activity. Mast cell-type granules were also observed ultrastructurally. The neoplastic infiltration was associated with fibrosis in the liver, spleen and bone marrow and with extramedullary hematopoiesis in the liver, spleen, lymph nodes and perihypophyseal tissue. The bone marrow showed uneven and multifocal involvement. Despite the lack of leukemic manifestations and the results of chromosomal analysis, the most suitable diagnosis was aleukemic basophilic leukemia within the category of chronic myeloproliferative disorder. Kinship of this neoplasia to systemic mastocytosis is discussed.

Basophils↗
PubMed2002

Flow cytometric basophil activation test: a review.

Flow cytometry is a technique enabling the analysis of physical and biological characteristics of cells or other biological particles when labeled with antibodies coupled to fluorochromes or other dyes. The basophil activation test (BAT), also called flow-cytometric allergen stimulation test (FAST) [commercially available under the name of Flow CAST (Bühlmann Laboratories) or BASOTEST (Beckton-Dickinson)] is based on the in vitro allergen-induced specific activation of basophils. This assay rests on the demonstration of some membrane protein markers that appear after exposure to the allergen. This paper reviews some of the literature about the use of this technique in the investigation of immediate-type allergies to inhalant allergens, drugs, and foods, as well as our own experience with this diagnostic technique. Flow cytometry is a reliable method for the quantification of basophil activation after allergenic stimulus in vitro and in vivo. It also enables us to detect allergic and pseudoallergic reactions because of other mechanisms than allergen-specific IgE antibodies. Further clinical evaluation of this technique will allow validation and better establishment of its diagnostic value in allergy.

Adult↗
PubMedDate not supplied

Immunomodulating properties of Minthostachys verticillata on human lymphocytes and basophils.

BACKGROUND: Minthostachys verticillata (Griseb.) Epling is a South American traditional medicinal herb used as digestive, anti-spasmodic, anti-inflammatory and bronchial dilator agent among other uses. Its anti-microbial activity against staphylococcal strains and its anti-viral properties against HVS-1 and strain RC/79 of PrV have been demonstrated. OBJECTIVE: To determine the immunomodulating ability of M. verticillata decoction and essential oil. As a complementary study, the main constituents of the essential oil were identified. MATERIALS AND METHODS: Lymphocyte-proliferating activity of both vegetal derivatives was tested and compared with cellular expansion induced by PHA, Pokeweed, CGB in cytomorphological study. A non-stimulate culture was used as control reference. The score of lymphocyte clusters and colonies was performed using the method described by Lange. Among proliferated cells, LT CD8+ subpopulation was characterized by direct immunofluorescence. The in vitro degranulant ability of the vegetal fractions was tested on basophils from allergic and non-allergic individuals sensitized to environmental fungi. Essential oil components of M. verticillata were identified by gas chromatography technique. RESULTS: M. verticillata derivatives reached higher proliferation levels compared to non-stimulated cultures, showed mitogenic activity and induced cluster and colony formation similar to PHA, Pokeweed and CGB. Cells that proliferated after stimulation with derivatives showed 40% of LT CD8+. Tested concentrations of decoction and essential oil did not reach minimum degranulation indexes over basophils, from both allergic and non-allergic individuals. Gas chromatography analysis revealed the presence of pulegone and menthone as the main constituents. CONCLUSIONS: M. verticillata derivatives were mitogenic over LT, inducing significant cluster and colony formation. There was no evidence of degranulating ability over basophils at the concentrations tested. We assume that the derivatives from M. verticillata would induce Th1 deviation in cellular cultures from allergic patients, which would diminish hypersensitivity reactions. Some of the compounds of the essential oil revealed by gas chromatography analysis may be responsible of the biological activity of these products.

Adolescent↗
PubMed2000

MMCP-8, the first lineage-specific differentiation marker for mouse basophils. Elevated numbers of potent IL-4-producing and MMCP-8-positive cells in spleens of malaria-infected mice.

In mice infected with the non-lethal malaria parasite Plasmodium chabaudi chabaudi AS, a prominent switch from a Th1 to a Th2 type of response occurs in CD4+ T cells at the time of peak parasitemia or shortly thereafter (9-15 days after infection). This is accompanied by a major increase in IL-4, and a similar decrease in IFN-gamma-producing cells. Non-B-non-T cells have been shown to be the main source of the IL-4 in these mice. The IL-4-producing cells are hyperresponsive to IL-3, indicating mast cell or basophil origin. To further characterize this cell population we have studied various organs at different time points of malarial infection by Northern blot analysis. No significant increase in the expression of any of the classical mouse mast cell serine proteases (MMCP)-1 to 7 or carboxypeptidase A was detected in the spleen during the entire infection. However, a marked increase in the expression of MMCP-8 was observed in the spleen at around day 15 post infection. Isolation of IgE receptor-positive cells from spleen shortly after peak parasitemia led to a prominent enrichment of MMCP-8-expressing cells. Fifty thousand of these cells were, after IL-3 stimulation, found to produce IL-4 to levels comparable with more than one million fully activated T cells. Our results show that basophil-like cells are very potent producers of IL-4 and that IL-4 produced by these cells may be of major importance for the initiation of a Th2 response. In addition, the detection of MMCP-8 in these cells has led to the identification of the first basophil-specific differentiation marker in the mouse.

Animals↗
PubMed2005

Flow cytometric analysis of in vitro activated basophils, specific IgE and skin tests in the diagnosis of pollen-associated food allergy.

BACKGROUND: Specific immunoglobulin E (IgE) and commercially available skin prick tests have been demonstrated to be unreliable methods to diagnose pollen-associated food allergy. To evaluate the predictive value of the basophil activation test (BAT) in pollen-associated food allergy, the apple-mediated oral allergy syndrome (OAS) in patients with birch pollinosis was chosen as a representative model. METHODS: Patients with birch pollen allergy and a history of apple-mediated OAS (OAS(+), n = 29), patients with birch allergic without OAS (OAS(-), n = 22), and healthy controls (HC, n = 10) without birch pollen allergy and OAS were included. Apple IgE was quantified by the CAP FEIA method. Skin prick tests were performed with a Jonagold apple extract. Flow cytometric analysis of basophils activated with the same Jonagold extract was based on double staining with anti-IgE/anti-CD63 monoclonal antibodies. RESULTS: Comparison between OAS(+) subjects and HC showed sensitivities and specificities of 96% and 100% for apple IgE and 88% and 100% for the apple skin prick test, respectively. For the BAT, sensitivity and specificity were 100%. In contrast, when nonresponders on the BAT were considered, sensitivity decreased to 90%. In a separate analysis between OAS(+) and OAS(-) subjects, specificities decreased to 30% for apple IgE and to 80% for the apple skin test, respectively. The BAT reached a sensitivity of 88% and a specificity of 75%. CONCLUSION: Flow cytometry-assisted quantification of in vitro basophil activation seems to be a reliable instrument in the diagnosis of this model of pollen-associated food allergy. In addition, this study reemphasizes that the specificity of diagnostic allergy tests decreases considerably when, apart from HC, control individuals with cross-reactive antibodies are included.

Adolescent↗
PubMed1993

CD21 expressed on basophilic cells is involved in histamine release triggered by CD23 and anti-CD21 antibodies.

Recombinant full-length human CD23 incorporated into fluorescent liposomes was used to detect a ligand for CD23 on the basophilic leukemia cell line, KU 812. Based on our recent finding that CD23 interacts with CD21 on subsets of B and T cells, we investigated if the same ligand was involved on KU 812 cells. An anti-CD21 monoclonal antibody (mAb) BU-33, was able to totally block CD23-liposome binding to KU 812 cells. Moreover, KU 812 cells express CD21 mRNA and have a cell surface molecule that reacts with anti-CD21 mAb. The CD23/CD21 interaction was not merely physical but was also associated with an increase in histamine release by KU 812 cells. Both recombinant soluble CD23 and an anti-CD21 mAb-mediated effect on histamine release was not restricted to and anti-CD21 mAb-mediated effect on histamine release was not restricted to the leukemic cell line, but was also observed with normal human blood basophils. These data demonstrate that CD21 is expressed on basophilic cells and that CD21 controls histamine production upon ligand-induced stimulation (CD23 or anti-CD21 mAb).

Antibodies, Monoclonal↗
PubMed1982

Isolation of a basophilic membrane protein binding the anti-allergic drug cromolyn.

The membrane protein component in basophils, responsible for the specific, Ca2+-dependent, binding of the anti-allergic drug cromolyn [disodium cromoglycate, DSCG; the disodium salt of 1,2 bis(2- carboxychromon -5- yloxy )-2-hydroxy propane] was isolated by two procedures based on affinity for the drug. In the first procedure, involving immunoprecipitation, rat basophilic leukemia cells (RBL-2H3), surface labeled by 125I were reacted with a polyvalent conjugate of DSCG and bovine serum albumin and then subjected to solubilization by the non-ionic detergent Nonidet P-40 (NP-40). From these lysates, precipitation was specifically attained by subsequent addition of rabbit anti-DSCG antibodies. In an SDS-polyacrylamide gel electrophoresis (SDS-PAGE), a single radioactive band was observed, having an apparent mol. wt. of 60 000 daltons. Competitive inhibition of the immunoprecipitation in the presence of free drug or excess of EDTA demonstrated the specificity of the isolation. Furthermore, this particular membrane component could not be isolated from several other cell types examined. The second isolation from several other cell types examined. The second isolation procedure employed affinity chromatography on DSCG immobilized on polyacryl- hydrazido agarose beads. The DSCG-binding protein was eluted from the affinity column with either DSCG or with EDTA and also migrated on SDS-PAGE as a single band of 60 000 mol. wt., similar to that obtained by the immunoprecipitation procedure. These and other results suggest that this newly isolated protein is the one responsible for the Ca2+-dependent binding of the drug to the basophil membrane.

Animals↗
PubMed1991

Stimulus-dependent leukotriene release from human basophils: a comparative study of C5a and Fmet-leu-phe.

Previous studies of human basophil mediator release have noted that the bacterial peptide fmet-leu-phe and the anaphylatoxin C5a induce comparable levels of histamine release while only fmet peptide induces leukotriene release. Since 5-lipoxygenase metabolism of arachidonic acid is calcium dependent, we examined the characteristics of the human basophil [Ca++]i response which follows its activation by either fmet peptide or C5a. While the peak [Ca++]i response was essentially identical for these two stimuli, fmet peptide induced a prolonged increase in [Ca++]i while C5a stimulated only a transient increase in [Ca++]i that was essentially over within 2 minutes of adding the stimulus. Simultaneous addition of EDTA with fmet peptide revealed the two phases of the [Ca++]i response and demonstrated that leukotriene release was dependent on an elevated [Ca++]i level in the 2-5 minutes following challenge. Enhancement of leukotriene release induced by C5a by agents such as staurosporine and interleukin-3 also produced a [Ca++]i kinetic curve which resembled fmet peptide. Single cell studies of the [Ca++]i response could detect no subpopulations of cells which responded preferentially to fmet peptide or C5a, eliminating the possibility that the ability of fmet peptide to induce leukotriene was a result of its action on a functionally distinct population of basophils.

Alkaloids↗
PubMed1993

Ultrastructural morphology of immature mast cells in sequential suspension cultures of human cord blood cells supplemented with c-kit ligand; distinction from mature basophilic leukocytes undergoing secretion in the same cultures.

The ability to culture human mast cells and, thus, to determine their ontogeny and possible relationships to other lineages has been facilitated by new studies using cocultures of cord blood cells with mouse fibroblasts and recombinant human or murine c-kit ligand-supplemented suspension cultures of cord blood cells. In this study, we examined c-kit ligand-supplemented cord blood cell suspension cultures designed so that the effects of growth factor source, individual cord sample, and culture time (3-17 weeks) on the developing mast cell lineage could be individually evaluated. We found that human mast cells, basophils, neutrophils, eosinophils, macrophages, megakaryocytes, and endothelial cells were present in these cultures. The numbers of mast cells and their granules increased with culture time; mature basophils, present in quantity in 3-week cultures, decreased in number and released granule contents with increased culture times. The mast cell lineage developed similarly, regardless of which factor preparation was added to cultures, but considerable variability existed among individual donors from whom cord bloods were obtained. Unlike the mature, crystal-containing mast cells that regularly developed in fibroblast cord blood cocultures (Furitsu et al. [1989] Proc. Natl. Acad. Sci. USA 86, 10039-10043), human mast cells failed to attain full maturity in the suspension cultures examined here, regardless of individual cord sample, added growth factor, or culture time. Furthermore, unlike cells of the basophil lineage in which granule content release was regularly observed, morphologic evidence of secretion from human mast cells was absent. Instead, these cells were actively undergoing granule building as determined by the increasing numbers of granules and filling of these containers over culture time. Crystal granules never developed, even at the maximum culture time of 17 weeks. We conclude that fibroblasts are necessary and sufficient for the differentiation and maturation of human mast cells in vitro from their agranular precursors in cord blood but that soluble c-kit ligand is not.

Animals↗
PubMed1994

Differential effects of cAMP-elevating drugs on stimulus-induced cytosolic calcium changes in human basophils.

Drugs that elevate cAMP levels in human basophils are known to inhibit immunoglobulin E (IgE)-mediated histamine release. We have examined whether cAMP-active agents inhibit the cytosolic Ca2+, [Ca2+]i, response that normally accompanies activation of basophils. As previously described, this [Ca2+]i response is biphasic, one phase dependent on internal sources of calcium and a second later phase dependent on extracellular calcium, as observed in many cell types. Forskolin and rolipram or their combination had no effect on the initial elevation of cytosolic calcium that follows stimulation with anti-IgE antibody. In contrast, the second phase of the IgE-mediated calcium response was inhibited by these agents. For IgE-mediated responses, the relative efficacy of various cAMP active agents (rolipram approximately forskolin < dibutyryl cAMP < forskolin + rolipram) for the inhibition of histamine release and the second-phase calcium response was similar and roughly paralleled the measured increase in basophil cAMP. In contrast, neither the first nor the second phase of the f-Met-Leu-Phe (fMLP)-induced calcium response was inhibited by any of the cAMP-active agents tested. Indeed, at low concentrations of fMLP, a combination of forskolin and rolipram caused slight enhancement of the calcium response. This result was consistent with the observations that these agents had no effect or caused slight enhancement of histamine or leukotriene released induced by fMLP. Similarly, cAMP-active agents caused no inhibition of C5a or phorbol ester (phorbol myristate acetate)-induced histamine release. These observations suggest that inhibition of the phase of the calcium response that is dependent on extracellular calcium could account for the inhibition of histamine release by these agents. However, these studies also suggested that (1) this is effect is not exerted at the level of the inositol trisphosphate (InsP3) receptor or InsP3 metabolism and (2) the mechanisms that maintain the second-phase calcium response are possibly distinct for IgE- and fMLP-mediated reactions because cAMP-active agents inhibited the second-phase response of only one stimulus.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Inhibitors of PI 3-kinase and MEK kinase differentially affect mediator secretion from immunologically activated human basophils.

Effects of inhibitors of PI 3-kinase and MEK kinases were investigated on histamine, leukotriene C4(LTC4), and cytokine release from human basophils stimulated with anti-IgE. The PI 3-kinase antagonists wortmannin (> 10 nM) and LY 294002 (>1 microM) strongly inhibited anti-IgE-induced release of all mediators by 40-100%. This was contrasted by the effects of the MEK kinase inhibitor PD 098059, which weakly inhibited histamine, interleukin (IL)-4, and IL-13 release but was substantially more efficacious at blocking LTC4 production (>70% at 10 microM). Previous studies have shown that arachidonic acid synthesis is controlled by MEK kinases. We observed that wortmannin, LY 294002, and PD 098059 reduce basophil ERK-1,2 activation, thus implying that, with regard to arachidonic acid metabolism, MEK kinases are a downstream target for PI-3-kinase. Our results demonstrate a universal regulatory role played by PI 3-kinases in basophil mediator production and release, whereas MEK kinase signaling is largely limited to controlling arachidonic acid metabolism.

Antibodies, Anti-Idiotypic↗