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At least 1,333 records · Page 74Linked to original sources
PubMed1980

Isolation and characterization of sulphated mucopolysaccharides from rat leukaemic (RBL-1) basophils.

Proteoglycans of 300 000 mol.wt. were isolated from dispersed rat basophil tumour cells after labelling of the sulphated mucopolysaccharides with 35S in vitro:90% of the 35S-labelled mucopolysaccharides were extracted at high salt concentration. Alkali degradation of the 35S-labelled proteoglycans yielded glycosaminoglycan chains of 40 000 mol.wt. The composition of the salt-extracted 35S-labelled mucopolysaccharides, as defined by parallel or sequential degradation with chondroitinase AC, chondroitinase ABC and heparinase and resolution of the disaccharide-digestion products obtained with chondroitinase AC, was 48--61% chondroitin 4-sulphate, 20--30% dermatan sulphate, 10--15% heparin and 7--9% chondroitin 6-sulphate. Most of the salt-extracted 35S-labelled mucopolysaccharides were highly charged, with heparin and chondroitin 6-sulphate being relatively uniform in this regard, whereas chondroitin 4-sulphate and dematan sulphate exhibited a range of charge characteristics. The diversity of sulphated mucopolysaccharides present in the rat leukaemic basophil is in contrast with the predominance of heparin in the rat mast cell.

Animals↗
PubMed2004

Isolation and characterization of lipid rafts with different properties from RBL-2H3 (rat basophilic leukaemia) cells.

Lipid rafts are plasma-membrane microdomains that are enriched in certain lipids (sphingolipids, glycosphingolipids and cholesterol), as well as in lipid-modified proteins. Rafts appear to exist in the liquid-ordered phase, which contributes to their partitioning from the surrounding liquid-disordered glycerophospholipid environment. DRM (detergent-resistant membrane) fractions isolated from cells are believed to represent coalesced lipid rafts. We have employed extraction using two different non-ionic detergents, Brij-96 and Triton X-100, to isolate detergent-resistant lipid rafts from rat basophilic leukaemia cell line RBL-2H3, and compared their properties with each other and with plasma-membrane vesicles. DRM fractions were isolated as sealed unilamellar vesicles of similar size (135-170 nm diameter), using either sucrose-density-gradient sedimentation or gel-filtration chromatography. Lipid rafts isolated using Brij-96 and Triton X-100 differed in density, protein content and the distribution between high- and low-density fractions of the known raft constituents, Thy-1, and the non-receptor protein tyrosine kinases, Yes and Lyn. Lyn was found in the raft microdomains in predominantly phosphorylated form. The level of enrichment of the protein constituents of the isolated lipid rafts seemed to depend on the ratio of cell lipid/protein to detergent. As indicated by reactivity with anti-Thy-1 antibodies, lipid rafts prepared using Brij-96 appeared to consist of vesicles with primarily right-side-out orientation. Both Brij-96 and Triton X-100 appear to isolate detergent-insoluble raft microdomains from the rat basophilic leukaemia cell line RBL-2H3, but the observed differences suggest that either the detergents themselves play a role in determining the physicochemical characteristics of the resulting DRM fractions, or different subsets of rafts are isolated by the two detergents.

Animals↗
PubMed2001

Basophils in chronic urticaria.

Blood basophils are reduced in chronic urticaria and respond less well to immunologic stimuli. Active recruitment of basophils from peripheral blood into lesional skin may be important in wheal pathogenesis.

Antibodies, Anti-Idiotypic↗
PubMed1997

Induction of human IgE synthesis in B cells by a basophilic cell line, KU812.

Induction of human IgE synthesis in B cells requires, in addition to IL-4 or IL-13, a second signal provided by CD40 ligand (CD40L) on activated Th2-type CD4+ T cells that do not or weakly express Fas ligand (FasL). Mast cells and basophils also produce IL-4 or IL-13 and express CD40L after immunologic or pharmacologic stimulation, although it is unknown whether these cells express FasL. This study investigated the capacity of KU812 cells, a human basophilic cell line, to produce IL-4 and IL-13, to express CD40L and FasL, and to induce IgE and IgG4 synthesis in human normal B cells. Upon stimulation of KU812 cells with either phorbol myristate acetate (PMA) or ionomycin (Iono), IL-4, but not IL-13, was produced in response to Iono, while IL-13, but not IL-4, was inducible by PMA. Moreover, both the time courses of IL-4 and IL-13 production and their amounts secreted were different; IL-4 production was transient, IL-13 production gradually increased, and IL-13 was heavily secreted as compared with IL-4. The combination of PMA and Iono (PMA/Iono) induced higher production of IL-4 or IL-13 than did Iono or PMA alone. KU812 cell-derived IL-4 and IL-13 had the ability to cause CD23 expression on B cells. PMA/Iono also up-regulated CD40L expression and induced a very low level expression of FasL. KU812 cells that had been activated by PMA/Iono followed by fixation could induce IgE and IgG4 synthesis in B cells in the presence of recombinant IL-4 or IL-13. This contact-dependent induction of IgE was completely abrogated by adding anti-CD40L MoAb or soluble CD40, whereas anti-FasL antibody did not significantly affect IgE production. These results indicate that activated KU812 cells produce biologically active IL-4 and IL-13, express functional CD40L, and exhibit weak induction of FasL, thereby supporting sufficient IgE production by B cells.

B-Lymphocytes↗
PubMed1996

The fibroblast mitogenic activity released from human basophilic cell line KU812 is separate from tryptase and PDGF expression.

The human leukaemia cell line KU812 has previously been used to study basophil differentiation. In this study the authors analysed the capacity of KU812 to produce the mast cell proteinase tryptase and to synthesize factor(s) mitogenic for fibroblasts. KU812 cells were treated with tetradecanoyl-phorbol-13-acetate (TPA), conditioned medium from the human T-cell line Mo (Mo-CM), or cultured under serum free conditions. After 4 days the cells were analysed for cell growth, differentiation, content of tryptase, and secretion of fibroblast mitogenic activity. Mo-CM and serum starvation increased the expression while TPA treatment down-regulated the expression of Fc epsilon RI-alpha chain. An increase in tryptase content in cell extracts was detected after 4 days of culture in serum-free medium or in the presence of Mo-CM. KU812 conditioned media was found to have a baseline expression of mitogenic activity on normal human foreskin fibroblasts that was increased after serum starvation or after treatment with TPA. Mast cell-derived tryptase has previously been reported to be mitogenic for fibroblasts, but in this study the expression of tryptase did not correlate with the expression of fibroblast mitogenic activity in KU812 cells. Furthermore, affinity-purified lung tryptase did not show any mitogenic activity. Platelet-derived growth factor was also excluded. Although the factor(s) from KU812 cells stimulating fibroblast proliferation have not been identified, our results indicate that basophils may be potential producers of growth factors inducing fibroblast proliferation.

3T3 Cells↗
PubMed2000

Identification of SAF-2, a novel siglec expressed on eosinophils, mast cells, and basophils.

BACKGROUND: Eosinophils, basophils, and mast cells are believed to be the central tenet cells in allergic conditions including allergic rhinitis, asthma, and eczema. The molecular mechanisms underlying the recruitment of these cells to sites of allergic inflammation are poorly understood. OBJECTIVES: Our aim was to identify a common adhesion molecule that could potentially be responsible for mediating the recruitment of the allergic cell types to the lungs and other sites of allergy. METHODS: We have cloned a sialoadhesin molecule from a human eosinophil library with the use of expressed sequence tag technology and characterized its expression on allergic cells by the use of flow cytometry and specific mAbs. RESULTS: With the use of expressed sequence tag sequencing, we have identified a novel siglec molecule, SAF-2. SAF-2 has homology with other sialoadhesin family members (CD33 and siglec-5) and belongs to a subgroup of the Ig superfamily. SAF-2 is a 431-amino acid protein composed of 3 Ig domains with a 358-amino acid extracellular domain and a 47-amino acid tail. SAF-2 is highly restricted to eosinophils, basophils, and mast cells. Antibodies to SAF-2 do not modulate Ca(++) mobilization or chemotaxis of human eosinophils induced by eotaxin. CONCLUSION: SAF-2 is a highly restricted sialoadhesin molecule, which may be useful in the detection and/or modulation of allergic cells.

Antigens, CD↗
PubMed2000

Systemic activation of basophils and eosinophils: markers and consequences.

Basophils and eosinophils are important effector cells in human allergic diseases; they play a significant role in promoting allergic inflammation through the release of proinflammatory mediators (such as histamine, leukotriene C(4), major basic protein, eosinophil cationic protein, IL-4, and IL-13, among others). Notably, in allergic subjects, these cells exist in higher numbers and in a more activated state compared with nonatopic control subjects. Evidence for the greater activation state includes increased expression of intracellular and surface markers and hyperreleasability of allergy mediators. We have been interested in the phenotypic markers of effector-cell activation for many years. There is considerable overlap among activation markers, and few activation markers have been found that define a unique phenotype that is quantifiable in the assessment of the presence and severity of allergic disease. This review summarizes the existing evidence for systemic activation of human basophils and eosinophils in allergic diseases. The potential mechanisms responsible for functional and morphologic alterations in these effector cells and the specificity and utility of surface markers in the assessment of allergic disease activity or severity are also discussed.

Basophils↗
PubMed1991

T-cell and basophil activation through the cytoplasmic tail of T-cell-receptor zeta family proteins.

The zeta chain of the T-cell antigen receptor is the prototype of a family of proteins that exist as disulfide-linked dimers and are subunits of the T-cell antigen receptor and both IgE and IgG binding Fc receptors. Two related genes encode the zeta and gamma proteins. In this study we examine the ability of chimeric proteins consisting of the extracellular domain of the alpha chain of the interleukin 2 receptor (Tac) and the cytoplasmic domain of either zeta or gamma to activate cells when expressed in either T cells or rat basophilic leukemia cells. The zeta and gamma chimera were effective at eliciting interleukin 2 production in T cells and serotonin release in rat basophilic leukemia cells when externally cross-linked. Cytoplasmic-tail deletion mutants of zeta and gamma were constructed and used to verify the specificity of cell activation by these chimeric proteins. Signaling potencies of complementary mutants having the zeta tail truncated in position 108 or deleted from positions 66 through 114 suggested the presence of several functional domains in zeta.

Amino Acid Sequence↗
PubMed1991

Mouse splenic and bone marrow cell populations that express high-affinity Fc epsilon receptors and produce interleukin 4 are highly enriched in basophils.

Splenic and bone marrow cells from normal mice, and from mice that have been polyclonally activated by injection of anti-IgD antibody, contain cells that produce interleukin 4 (IL-4) in response to crosslinkage of Fc epsilon receptors (Fc epsilon R) or Fc gamma R or to ionomycin. Isolated Fc epsilon R+ cells have recently been shown to contain all of the IL-4-producing capacity of the nonlymphoid compartment of spleen and bone marrow. Here, purified Fc epsilon R+ cells are shown to be enriched in cells that contain histamine and express alcian blue-positive cytoplasmic granules. By electron microscopy, the vast majority of cytoplasmic granule-containing cells are basophils; they constitute approximately 25% and approximately 50%, respectively, of Fc epsilon R+ spleen and bone marrow cells from anti-IgD-injected mice. The Fc epsilon R- populations contain cells that form colonies typical of mast cells. The Fc epsilon R+ populations also contain cells that, upon culture with IL-3, form colonies of alcian blue-positive cells, but (in contrast to colonies derived from Fc epsilon R- populations) the colonies are small, and all the cells die within 2-3 weeks. The Fc epsilon R+ cells synthesize histamine during a 60-hr culture with IL-3, while the Fc epsilon R- cells do not. These results indicate that IL-4-producing Fc epsilon R+ cells are highly enriched in basophils.

Animals↗
PubMed2001

Extranuclear lipid bodies, elicited by CCR3-mediated signaling pathways, are the sites of chemokine-enhanced leukotriene C4 production in eosinophils and basophils.

Eosinophils and basophils, when activated, become major sources of cysteinyl leukotrienes, eicosanoid mediators pertinent to allergic inflammation. We show that the C-C chemokines, eotaxin and RANTES (regulated upon activation normal T cell expressed and secreted), activate eosinophils and basophils for enhanced leukotriene C(4) (LTC(4)) generation by distinct signaling and compartmentalization mechanisms involving the induced formation of new cytoplasmic lipid body organelles. Chemokine-induced lipid body formation and enhanced LTC(4) release were both mediated by CCR3 receptor G protein-linked downstream signaling involving activation of phosphoinositide 3-kinase, extracellular signal-regulated kinases 1 and 2, and p38 mitogen-activated protein kinases. Chemokine-elicited lipid body numbers correlated with increased calcium ionophore-stimulated LTC(4) production; and as demonstrated by intracellular immunofluorescent localization of newly formed eicosanoid, lipid bodies were the predominant sites of LTC(4) synthesis in both chemokine-stimulated eosinophils and chemokine-primed and ionophore-activated eosinophils. Eotaxin and RANTES initiated signaling via phosphoinositide 3-kinase and mitogen-activated protein kinases both elicits the formation of lipid body domains and promotes LTC(4) formation at these specific extranuclear sites.

Basophils↗
PubMed2002

Indomethacin causes prostaglandin D(2)-like and eotaxin-like selective responses in eosinophils and basophils.

We investigated the actions of a panel of nonsteroidal anti-inflammatory drugs on eosinophils, basophils, neutrophils, and monocytes. Indomethacin alone was a potent and selective inducer of eosinophil and basophil shape change. In eosinophils, indomethacin induced chemotaxis, CD11b up-regulation, respiratory burst, and L-selectin shedding but did not cause up-regulation of CD63 expression. Pretreatment of eosinophils with indomethacin also enhanced subsequent eosinophil shape change induced by eotaxin, although treatment with higher concentrations of indomethacin resulted in a decrease in the expression of the major eosinophil chemokine receptor, CCR3. Indomethacin activities and cell selectivity closely resembled those of prostaglandin D(2) (PGD(2)). Eosinophil shape change in response to eotaxin was inhibited by pertussis toxin, but indomethacin- and PGD(2)-induced shape change responses were not. Treatment of eosinophils with specific inhibitors of phospholipase C (U-73122), phosphatidylinositol 3-kinase (LY-294002), and p38 mitogen-activated protein kinase (SB-202190) revealed roles for these pathways in indomethacin signaling. Indomethacin and its analogues may therefore provide a structural basis from which selective PGD(2) receptor small molecule antagonists may be designed and which may have utility in the treatment of allergic inflammatory disease.

Antigens, CD↗
PubMed2004

CD200 receptor family members represent novel DAP12-associated activating receptors on basophils and mast cells.

Modulation by balancing activating and inhibitory receptors constitutes an important mechanism for regulating lymphocyte and myeloid cell effector responses. Using a microarray screen during parasitic helminth infection, we identified CD200 receptor-like 3 as a transcript highly expressed in basophils. Novel splice variants were present that generated proteins that differed in surface expression. The second immunoglobulin-like domain, encoded by exon 4, was required for cell surface expression and recruitment of DAP12 to the cell surface. Splice variants also generated unique cytoplasmic domains, which contributed to efficient pairing with DAP12. Despite expression on basophils and mast cells, which are integral components of allergic immunity, the absence of DAP12 did not alter effector cell recruitment or the host response elicited by helminth infection with Nippostrongylus brasiliensis.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Acute basophilic leukemia with t(8;21).

Acute basophilic leukemia (ABL) is a rare form of leukemia. The diagnostic criteria have recently been described. Morphological evidence for basophilic lineage is required for its classification. However the criteria for remission status and standard therapy is not established. Here we have described an atypical case of ABL and reviewed the literature to high light issues regarding diagnosis and management, which need further discussion.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Clustering, mobility, and triggering activity of small oligomers of immunoglobulin E on rat basophilic leukemia cells.

We have recently shown that small oligomers of IgE bound to univalent receptors for IgE on the surface of rat basophilic leukemia cells induce extensive aggregation of the receptors at 4 degrees C into patches resolvable by fluorescence microscopy and that this does not occur with monomeric IgE (Menon, A. K., D. Holowka, and B. Baird, 1984, J. Cell Biol. 98:577-583). Here we use fluorescence photobleaching recovery measurements to show that receptor oligomerization by this means is accompanied by a dramatic reduction of receptor lateral mobility, and that this immobilization occurs even when the clustering is not microscopically detectable. Furthermore, the degree of immobility induced by a particular oligomer fraction from a gel filtration column correlates positively with its ability to trigger cellular degranulation, whereas receptors labeled with monomeric IgE have no triggering activity and exhibit typical membrane protein mobility. The slow, large-scale oligomer-induced clustering appears to be a long term consequence of earlier selective interactions that result in receptor immobilization, and this highly clustered state provides a competent, noninhibitory triggering signal resulting in cellular degranulation upon warming to 37 degrees C. We conclude that even limited clustering of IgE receptors on rat basophilic leukemia cells induces interactions with other cellular components that constrain receptor mobility and eventually cause massive coalescence of the clusters. These primary selective interactions occurring at the level of receptor oligomers or small clusters of oligomers that result in immobilization may play a role in triggering cellular degranulation.

Animals↗
PubMed1987

Depolarization of rat basophilic leukemia cells inhibits calcium uptake and exocytosis.

We have investigated the unusual observation that depolarization of rat basophilic leukemia cells in high potassium not only fails to induce secretion, but also inhibits the secretion induced when receptors for IgE are aggregated by antigen. Antigen-stimulated 45Ca uptake and the rise in cytoplasmic free ionized calcium measured with the fluorescent indicator quin2 were both inhibited in depolarized cells. 45Ca efflux, on the other hand, was unaffected, which confirms that IgE receptor activation was not impaired in high potassium. Unlike the large increase in total cell calcium seen when cells in normal saline solution were stimulated with antigen, there was a decrease in total cell calcium when depolarized cells were stimulated. This is consistent with our finding that 45Ca uptake was inhibited while 45Ca efflux was unaffected. Inhibition of 45Ca uptake and secretion closely paralleled the decrease in membrane potential, and could be overcome by increasing the extracellular calcium concentration. We conclude that changes in the electrochemical gradient for calcium are important in determining calcium influx and the magnitude of antigen-stimulated secretion from rat basophilic leukemia cells, while the release of calcium from intracellular stores is unaffected.

Animals↗
PubMed1984

Small oligomers of immunoglobulin E (IgE) cause large-scale clustering of IgE receptors on the surface of rat basophilic leukemia cells.

We examined the distribution of small oligomers of IgE bound to rat basophilic leukemia cells using fluorescence microscopy. The oligomers were seen to cluster into visible patches on the cell surface at 4 degrees C; at higher temperatures internalization also was observed. In contrast, cells labeled with IgE monomers remained predominantly ring-stained. Evidence is provided that the observed clustering of IgE oligomers is a cell-induced phenomenon, and the possible significance of this clustering is discussed in the context of the oligomer-triggered degranulation of rat basophilic leukemia cells.

Animals↗
PubMed1971

Cutaneous basophil (Jones-Mote) hypersensitivity after "tolerogenic" doses of intravenous ovalbumin in the guinea pig.

Cutaneous basophil hypersensitivity (CBH) was studied for tolerogenic requirements. Graded doses of intravenous ovalbumin (OA) were given to guinea pigs which were subsequently immunized appropriately to produce CBH, classic delayed hypersensitivity (classic DH), and/or antibodies of both passive cutaneous anaphylaxis (PCA) and hemolytic types. Results showed that doses of intravenous antigen sufficient to induce subsequent tolerance for classic DH and hemolytic antibody actually stimulate CBH reactivity and PCA antibody production. Other studies of dose-route relationships for CBH production demonstrated that optimal immunogenic dosage requirements for CBH varied widely with route of antigen employed. OA in incomplete Freund's adjuvant (IFA) injected into footpads had low dosage requirements, intravenous OA had high dose requirements, and intradermal soluble OA dosage requirements were intermediate. The observation that blatant immunogenic responses occur during the early period of tolerance induction amplifies the significant heterogeneity of the cellular immune response and may be of importance in understanding tolerogenesis. Similar immunogenic-tolerogenic requirements and the prime role played by the basophil suggest a developmental or functional relationship between CBH and PCA antibody response.

Animals↗
PubMed1972

Leukocyte-dependent histamine release from rabbit platelets. The role of IgE, basophils, and a platelet-activating factor.

We have studied the leukocyte-dependent mechanism of histamine release (LDHR) from rabbit platelets, a complement-independent mechanism which has been implicated in the deposition of immune complexes in acute serum sickness of rabbits. It was found by chromatography and passive transfer of serum from immunized rabbits that the antibody responsible for the LDHR was of IgE type. By electron microscope study of the reaction, the leukocyte involved in agglutination of platelets and release of their histamine content was identified as the basophil. Upon addition of antigen, basophils sensitized with IgE degranulated, released their histamine content and a platelet-activating factor (PAF) that caused aggregation of platelets and release of their histamine. Conditions of preparing and preserving PAF activity and some properties of this factor have been elucidated. LDHR must, therefore, be considered as an immediate hypersensitivity-type mechanism which may link allergic reactions with immunologic disease associated with severe structural injury.

Animals↗