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Differential regulation of IL-4 and IL-13 secretion by human basophils: their relationship to histamine release in mixed leukocyte cultures.

Human basophils are an important source of IL-4, a cytokine that is central to the pathogenesis of allergic inflammation. Recent reports have indicated that these cells also generate IL-13, which shares a number of biologic properties with IL-4. We found basophils to be the major source of IL-13 produced in mixed leukocyte cultures following 20-h activation with a variety of stimuli. While the magnitude of IL-4 protein generated correlated with the percent histamine secreted (r = 0.8; p = 0.007), there was no relationship between the levels of IL-13 detected and the amount of either IL-4 or histamine in cultures activated with IL-3/anti-IgE. The induction of IL-13 secretion also occurred in response to IL-3 alone, without concomitant secretion of either IL-4 or histamine. Although previously shown to inhibit IL-4 secretion, the phorbol ester PMA was a potent stimulus for IL-13 generation from basophils, and this secretion was sensitive to the protein kinase C inhibitor, bisindolylmaleimide. In contrast, bisindolylmaleimide did not prevent cytokine secretion induced by either anti-IgE or IL-3. The immunosuppressant, FK506, while strikingly inhibiting the accumulation of IL-4 mRNA and the secretion of protein in response to IL-3/anti-IgE, had no effect on the generation of IL-13 in these cultures; the resistance was attributed to the IL-3-dependent signaling. Similarly, FK506 had no effect on the secretion of IL-13 in basophil cultures stimulated with PMA. This study suggests that multiple intracellular mechanisms control the generation of IL-13 in basophils, some of which are distinct from those regulating IL-4.

Adult↗

Expression of protein kinase C isozymes in human basophils: regulation by physiological and nonphysiological stimuli.

The expression of protein kinase C (PKC) isozymes in human basophils and the regulation of PKC isozymes during basophil activation by phorbol 12-myristate 13-acetate (PMA) +/- ionomycin, f-met-leu-phe (FMLP), and anti-IgE antibody were examined. In human basophils (> 98% purity), PKCbetaI, betaII, delta, and were expressed, PKCalpha was difficult to detect, and PKCgamma and eta were undetectable. In unstimulated basophils, PKCbetaI and betaII were found primarily in the cytosol fraction (95% +/- 3% of total and 98% +/- 1%, respectively). Within 5 minutes of stimulation with PMA (100 ng/mL), both PKCbetaI and betaII were translocated to the membrane fraction (85% +/- 4% and 83% +/- 6%, respectively). In resting cells, 48% +/- 3% and 61% +/- 10% of PKCdelta and , respectively, existed in the membrane fraction. Within 1 minute of stimulation with PMA, 90% +/- 6% of PKC was found in the membrane fraction, however, no translocation of PKCdelta was apparent. Stimulation with FMLP caused modest translocation ( approximately 20%) of all PKC isozymes by 1 minute, whereas stimulation with anti-IgE antibody led to no detectable changes in PKC location throughout a 15-minute period of measurement. However, concentrations of PMA and ionomycin that alone caused no PKC translocation and little histamine release, together caused significant histamine release but no apparent PKC translocation. Studies with bis-indolylmaleimide analogs showed inhibition of PMA-induced, but not anti-IgE-induced, histamine release. These pharmacological studies suggest that PKC does not play a prodegranulatory role in human basophil IgE-mediated secretion.

Antibodies, Anti-Idiotypic↗

Effects of dental amalgam and its components of histamine release from human basophils and tissue mast cells.

Recent studies have shown that metal ions can be released from dental amalgam or other dental materials, and can cause toxic effects on various cells. In this study, the effects of amalgam-conditioned culture medium (ACCM), components of amalgam (Ag+, Cu2+, Sn2+, Hg2+) and dental composite-conditioned culture medium (CCCM) on histamine release from human blood basophils (healthy subjects, n = 3) and tissue mast cells (n = 3) were analyzed. ACCM and CCCM were prepared using either fresh or 6-weeks-aged specimens. Of the metal ions tested, Ag+, and Hg2+ were found to induce histamine release from basophils (Ag+, 0.33 mM: 83 +/- 11% vs Hg2+, 0.33 mM: 100% vs control medium: 5 +/- 5%) and mast cells (Ag+, 0.33 mM: 91 +/- 16% vs Hg2+, 0.33 mM: 99 +/- 1% vs control: 2 +/- 1%), whereas no effects were seen with Cu2+ and Sn2+. Neither ACCM from freshly prepared amalgam nor ACCM from 6-weeks aged amalgam, produced histamine release in basophils or mast cells. Inductively coupled plasma atomic emission spectrometry (ICP) revealed that the Ag(+)- and Hg(2+)-concentrations in ACCM were below the range in which histamine release occurred. Similar to ACCM, no effects on basophils or mast cells were observed with CCCM. In summary, our data show that distinct metal ions present in dental amalgam, can induce (toxic) histamine liberation from basophils and mast cells. However, the amounts of metal ions released from amalgam apparently were too low, to cause histamine release.

Basophils↗

Identification of basophilic cells that express mast cell granule proteases in the peripheral blood of asthma, allergy, and drug-reactive patients.

Metachromatic cells in the peripheral blood of patients with asthma, allergy, or an allergic drug reaction were evaluated for their nuclear morphology, surface expression of the mast cell (MC) marker c-kit, surface expression of the basophil marker Bsp-1, and granule expression of MC proteases. Consistent with previous findings by others, Bsp-1+/metachromatic cells represented <1% of the cells in the peripheral blood of normal individuals. These cells generally contained segmented nuclei. Very little, if any, tryptase (Try), chymase (Chy), or carboxypeptidase A (CPA) was found in their granules, and very little, if any, c-kit was observed on their surfaces. The number of metachromatic cells increased in the peripheral blood of the three groups of patients. Like the basophils in normal individuals, most of these metachromatic cells contained segmented nuclei and expressed Bsp-1. However, in contrast to the basophils in normal individuals, many of the metachromatic cells in the three patient groups expressed c-kit, Try, Chy, and/or CPA. That the metachromatic cells in the blood of our patients have some features of MCs and some features of basophils suggests that human basophils and MCs are derived from a common progenitor. As assessed by the chloroacetate esterase cytochemical assay, the immunoreactive Chy in the peripheral blood of these patients is enzymatically active. Because MC proteases regulate numerous immunologic and other biologic systems, the expression of Try, Chy, and/or CPA in a peripheral blood-localized cell in an individual having asthma, allergy, or an allergic drug reaction has important clinical implications.

Acute Disease↗

Biological potential of basophilic hepatocellular foci and hepatic adenoma induced by the peroxisome proliferator, Wy-14,643.

The biological potential of hepatic foci and tumors induced by peroxisome proliferators such as Wy-14,643 has been poorly characterized. In this study, male F-344 rats (n = 20/group/time point) were fed Wy-14,643 (0.1%) for 22, 37 or 52 weeks ('W-22', 'W-37' or 'W-52' respectively). At each time point some rats were killed and additional Wy-14,643-fed rats were switched to basal diet (Wy-14,643/'stopped') for up to 104 weeks (referred to as 'W-22/S', 'W-37/S' and 'W-52/S'). Homogeneous basophilic foci, but not clear cell foci, increased in number and size in W-37 and W-52 rats. In W-37/S rats, clear cell foci replaced basophilic foci as the most frequent phenotype. In serial section overlays, adenosine triphosphatase deficient foci accounted for only 16% of basophilic foci in W-52 rats and 16% of clear cell foci in W-37/S rats at 52 weeks. The replication of basophilic foci of W-37 rats was markedly increased (focal labeling index, FLI = 61.8% versus non-focal labeling index, LI = 11.4%; control LI = 0.8%). Clear cell foci from W-37/S rats at 52 weeks had a FLI of 1.6% (non-focal LI = 0.6%). Hepatocellular adenomas were increased in W-37 (11/20 rats and 0.8 tumors/rat) and W-52 groups (19/20 rats and 2.8 tumors/rat). Prevalence of hepatocellular carcinomas was elevated in W-52 rats (6/20 rats) but not in W-22 or W-37 rats. Following removal of Wy-14,643, prevalence of animals with malignant, metastatic hepatocellular carcinomas in W-52/S rats was similar to the prevalence in W-52 rats. However, Wy-14,643-induced adenomas completely regressed in W-37/S and W-52/S groups. In summary, significant morphological continuity between highly proliferative basophilic foci and hepatocellular tumors was identified, emphasizing the superiority of basophilia as a marker for lesions leading to development of hepatocellular neoplasia in rats fed Wy-14,643. An important biological distinction was noted between regressive hepatic adenomas and progressive hepatocellular carcinomas induced by a peroxisome proliferator.

Adenoma, Liver Cell↗

Simultaneous initiation of degranulation and inhibition of leukotriene release by soman in human basophils.

Previous studies noted that the serine esterase inhibitor, soman, could induce histamine release from human basophils. To investigate the mechanisms by which soman causes histamine release (a preformed mediator), we also examined its ability to induce leukotriene release (a newly synthesized mediator) from basophils. We found that no leukotriene release followed activation with soman, while histamine release was usually greater than 70%. In addition, soman and diisopropyl-fluorophosphate were found actively to suppress low level spontaneous leukotriene release as well as ongoing leukotriene release induced by anti-IgE antibody. Soman (0.3 mM) was able to stop leukotriene release as rapidly as the calcium chelator, EDTA. In a series of control experiments, it was noted that soman did not influence the metabolism of LTC4 to LTD4 or LTE4 (for which little metabolism occurred), eliminating the possibility that reduced LTC4 release could have resulted from its enhanced metabolism. Therefore, using one compound (soman), basophils could be simultaneously activated to degranulate while having the pathway leading to leukotriene release actively suppressed. These results provide further evidence that histamine and leukotriene release are independent pathways resulting from the activation of basophils.

Basophil Degranulation Test↗

Involvement of Rab27 in antigen-induced histamine release from rat basophilic leukemia 2H3 cells.

The Rab family small G proteins regulate discrete steps in vesicular transport pathways. Recent studies indicate that one member of the Rab family, Rab27A, regulates the transport of lysosome-related organelles, such as melanosome distribution in melanocytes, lytic granule release in cytotoxic T cells, and dense granule release in platelets. Here, we have examined the involvement of Rab27A in the exocytic transport of another lysosome-related organelle, the basophilic secretory granule, in basophils. We have found that Rab27A locates on basophilic secretory granules containing histamine in rat basophilic leukemia (RBL) 2H3 cells. In addition, exogenous expression of dominant active Rab27A reduces antigen-induced histamine release from the cells. We have moreover identified Munc13-4 as a Rab27A target using a CytoTrap system and found that exogenous expression of Munc13-4 affects antigen-induced histamine release from RBL-2H3 cells. These results demonstrate that Rab27A plays a crucial role in antigen-induced histamine release from RBL-2H3 cells.

Animals↗

[Basophilic differentiation of leukemic cells in a patient with acute leukemia carrying minor bcr/abl chimeric mRNA].

A 77-year-old woman was referred to our hospital because of leukocytosis and leukoblastosis in September 1999. She was healthy except for hypertension, and no abnormal findings in the peripheral blood had been observed up to December 1998. Physical examination revealed neither hepatosplenomegaly nor superficial lymphadenopathy. A bone marrow film showed massive proliferation of blast cells (87.8%), some of which contained coarse basophilic granules (38.6%). The cells were negative for peroxidase and esterase (alpha-naphtyl butyrate and ASD-chloroacetate) staining, but the granules showed metachromasia upon toluidine blue staining. As immunophenotypic analysis of the cells showed double positive for CD13/CD19 but negativity for CD33, this case did not meet the diagnostic criteria for biphenotypic acute leukemia. Chromosome and gene analysis showed positivity for the Ph1 chromosome with minor bcr/abl chimeric mRNA. A homogenate of the peripheral mononuclear cells demonstrated a high concentration of histamine. Electron microscopy analysis confirmed that some of the blast cells contained dense granules, which closely resembled "immature basophil granules" morphologically. These results suggested that the blast cells showed basophilic differentiation. As the clinical course and peripheral blood findings were different from blastic crisis of chronic myelogenous leukemia (CML) and CML with minor bcr/abl chimeric mRNA, the present case was diagnosed as "multiphenotypic acute leukemia", a type of acute basophilic leukemia classified by Duchayne.

Aged↗

[Study on basophil releasability induced by anti-IgE in allergic rhinitis].

We have investigated the basophil releasability induced by anti-IgE in allergic rhinitis patients and normal subjects by reverse human basophil degranulation tests. The results showed that anti-IgE-mediated basophil releasability and total serum IgE were significantly higher in allergic rhinitis patients than that in normal subjects. However, anti-IgE-mediated basophil releasability, total serum IgE and blood eosinophil count were not closely correlated with each other.

Basophil Degranulation Test↗

MAFA-L, an ITIM-containing receptor encoded by the human NK cell gene complex and expressed by basophils and NK cells.

The natural killer cell gene complex on human chromosome 12p12-13 encodes several C-type lectin receptor genes expressed by NK cells and other hematopoietic cells. We have identified a novel receptor gene in this region encoding a putative type II transmembrane glycoprotein. The product is 54% identical to the rat mast cell function-associated antigen (MAFA), which inhibits mast cell activation by IgE. The human MAFA-like receptor (MAFA-L) and the rat MAFA protein are expressed by basophils and both have an immunoreceptor tyrosine-based inhibitory motif in the cytoplasmic tail, consistent with an inhibitory role in basophil activation. Unlike rat MAFA, expression of the MAFA-L gene is not limited to mast cells and basophils. In common with other genes in the NK cell gene complex MAFA-L is also expressed by natural killer cells as well as the monocyte-like cell-line U937. Expression in NK cells is restricted to peripheral blood NK cells, decidual NK cells do not express MAFA-L. While MAFA-L and rat MAFA might have a similar role in basophils, the expression of MAFA-L in other cell types implies additional functions for this molecule. The presence of the MAFA-L gene in the human NK cell complex indicates that this locus encodes C-type lectin receptors expressed by a variety of cells important in host defense.

Amino Acid Sequence↗

Regulation of cytokine expression and leukotriene formation in human basophils by growth factors, chemokines and chemotactic agonists.

Basophils stimulated with IL-3 plus C5a selectively express IL-4 and IL-13 and continuously produce leukotrienes (LT) for hours. C5a combined with IL-5 or granulocyte-macrophage colony-stimulated factor was, however, much less effective in promoting cytokine expression and a late continuous phase of LTC4 production, possibly due to lower expression levels of their receptor alpha chains. Basophils also express several chemoattractant receptors, including high levels of C5a receptors, macrophage chemotactic protein (MCP) receptors (CCR2) and eotaxin receptors (CCR3), intermediate levels of CXCR1, CXCR2 and platelet-activating factor receptors, and lower levels of N-formyl-Met-Leu-Phe (fMLP) receptors. However, among the corresponding agonists, only C5a, fMLP and much more weakly MCP1, were found to induce cytokine expression and continuous LTC4 release, and only when combined with IL-3. CCR3, which is highly expressed on basophils and has been shown to mediate strong migratory but weak release responses, does not regulate cytokine expression. The weakly expressed fMLP receptor is an efficient activator of several cell functions including LTC4 formation, while CXCR2 hardly affects basophil function despite considerable expression. Thus, chemoattractant-receptors mediate different cellular responses unrelated to their expression levels.

Basophils↗

Murine mast cell lines as indicators of early events in mast cell and basophil development.

To study early events in mast cell / basophil development, the phenotype of a panel of murine cell lines at various stages of differentiation was determined. Based on the expression on various mast cell-specific proteases and several additional hematopoietic differentiation markers, the cell lines CFTL-15 and MCP5 / L were clearly identified as mast cells, although with a relatively immature phenotype. These two cell lines express the high-affinity IgE receptor alpha-chain, the mouse mast cell protease (MMCP)-5 and the carboxypeptidase A (CPA). Bone marrow-derived mast cells and the transplantable mast cell tumor MTC were shown to express the IgE receptor alpha-chain, MMCP-5 and CPA, as well as the mast cell tryptase MMCP-6 and the chymase MMCP-4, a protease expressed only during late stages of mast cell differentiation. These two cell types thus display a more mature mast cell phenotype. In contrast, the cell lines P815 and 32D cl3 did not express any mast cell differentiation markers. Interestingly, the IC-2 cell line was shown to express several markers for immature mast cells and in addition MMCP-8, a serine protease which may represent a marker for mouse basophils. By antibody staining, almost all IC-2 cells were shown to express MMCP-8. This indicates that individual cells may simultaneously express both mast cell and basophil markers. Moreover, these findings suggest that an early branch point in hematopoietic development where mast cells and basophils have a common precursor cell may exist.

Animals↗

Prognostic implications of basophil differentiation in chronic myeloid leukemia.

Basophilia has been reported to indicate an accelerated phase of chronic myeloid leukemia (CML), heralding a poor prognosis. We have studied 47 patients with chronic-phase CML by basophil growth and differentiation assays in vitro, demonstrating an association between basophil growth index (BGI) and clinical time to blast crisis as well as overall survival. In addition to confirming an association between positive BGI and phase of CML in a larger group of patients, a positive BGI predicted death or blast crisis within 2 years' study of chronic phase CML (p less than 0.01), with a sensitivity of 78%, specificity, 81%; the positive predictive value of a positive test, 64%; and a negative predictive value of a negative test, 89%. The survival experience of the 22 evaluable patients with chronic-phase CML and a positive BGI was significantly worse than the survival of the 19 patients with a negative BGI (p less than 0.0001). At 1, 2, and 3 years the proportion of surviving patients with a positive BGI was 0.64, 0.32, and 0.23, respectively, compared with 1.00, 0.90, and 0.79 for those with a negative BGI. The median survival of chronic phase CML patients with a positive test at diagnosis (n = 14) was 27 months versus 54 months for those with a negative diagnosis (n = 14) (p less than 0.05). These findings emphasize the prognostic utility of basophil growth assays in CML and suggest a molecular relationship between leukemic transformation and basophil lineage expression.

Basophils↗

Immunoelectron microscopic localization of galectin-3, an IgE binding protein, in human mast cells and basophils.

Galectin-3 is an endogenous soluble lectin within the family called galectins that bind beta-galactosides. Homologs of the protein isolated from different sources were previously designated as IgE-binding protein (epsilon BP), CBP35, CPB30, Mac-2, RL-29, RLL, L-29, and HL-29. All are now renamed galectin-3. This lectin is widely distributed in cells and tissues of mice, rats, dogs, hamsters, and humans. Light microscopic immunohistochemistry and ultrastructural immunogold labeling methods were used to determine the distribution of galectin-3 in human mast cells of several organs, in mast cells developed in vitro from human fetal liver cells, and in human peripheral blood basophils. Immunolabeling for the protein was observed in mast cells from all sources and in basophils. The lectin was detected in the nucleus and/or the cytoplasm. The nuclear labeling was over heterochromatin whereas euchromatin was unlabeled. Cytoplasmic labeling was concentrated over secretory granules. The intensity of staining generally was greater in mast cells of skin when compared with that of mast cells in other locations and with that of basophils. Studies have indicated that in mast cells galectin-3 may be involved in promoting their adhesion to basal laminae. In this study the localization of galectin-3 in the secretory granules of human mast cells and basophils suggests that these cells may release this lectin when activated to degranulate.

Adult↗

Differential activation of human basophils by anti-IgE and formyl-methionyl-leucyl-phenylalanine. Indications for protein kinase C-dependent and -independent activation pathways.

Upon activation, basophilic granulocytes release inflammatory mediators such as histamine. We studied histamine release of human basophils (64.1 +/- 9.6% pure) after cross-linking of membrane-bound IgE via anti-IgE, or after binding of the chemoattractant formyl-methionyl-leucyl-phenylalanine (fMLP). A variability in the extent of histamine release upon stimulation by either anti-IgE or fMLP was found between donors. Kinetic studies revealed that the histamine release induced by anti-IgE (t1/2 greater than 240 s) was more than 20-fold slower than the almost instantaneous release upon stimulation with fMLP (t1/2 less than 10 s). Differences in the cell activation pathways triggered by these stimuli were further analyzed with staurosporine, an inhibitor of protein kinase C (PKC) and with wortmannin, an inhibitor of a PKC-independent pathway. Inhibition of PKC resulted in a partial inhibition of the anti-IgE-induced release, whereas the fMLP-induced release was slightly potentiated. The anti-IgE-induced release was completely inhibited in the presence of wortmannin. This inhibitor too, had no effect on the fMLP-induced release. We conclude that major differences exist in the signal-response coupling between the anti-IgE and fMLP-induced histamine release in human basophils. The so-called releasability of human basophils may be due to the availability of different cell activation pathways.

Alkaloids↗

Signal transduction for interleukin-3-dependent leukotriene synthesis in normal human basophils: opposing role of tyrosine kinase and protein kinase.

The intracellular signaling pathways regulating the synthesis of leukotrienes by myeloid cells are largely unknown. In addition, the signal transduction mechanisms utilized by the cytokine receptor family are still poorly understood. The fact that in mature human basophils the synthesis of leukotriene C4 (LTC4) induced by C5a is strictly dependent on a short preincubation with the cytokine interleukin-3 (IL-3), allowed us to investigate the metabolic requirements for LTC4 synthesis, and also to provide some information on early signal transduction mechanisms of IL-3 in these differentiated, non-dividing blood leukocytes. IL-3 itself does not alter intracellular free calcium concentration ([Ca2+]i) in basophils, whereas C5a induces a transient rise independent of IL-3 pretreatment, indicating that the priming effect of IL-3 cannot be explained by alterations in [Ca2+]i changes. The protein kinase C inhibitor staurosporine did not inhibit C5a-induced histamine release nor IL-3-dependent LTC4 formation in contrast to the IgE receptor-dependent basophil response. Activation of protein kinase C (PKC) by phorbol-12-myristate-13-acetate (PMA) induced histamine release without leukotriene formation. PMA-treated basophils did not produce LTC4 in response to C5a. Rather, PMA blocked the IL-3 effect on C5a-induced LTC4 synthesis. Only the C5a signal but not the IL-3 effect was pertussis toxin sensitive. Two unrelated tyrosine kinase inhibitors, tyrphostin RG-50864 and herbimycin A, were both very efficient blockers of IL-3-dependent lipid mediator formation whereas C5a-induced histamine release was preserved. Thus LTC4 formation does not require activation of a staurosporine-sensitive serine/threonine kinase. To the contrary, IL-3-dependent LTC4 formation appears to be regulated by serine/threonine and tyrosine phosphorylation in an antagonistic manner.

Alkaloids↗

Purified human peripheral blood basophils release interleukin-13 and preformed interleukin-4 following immunological activation.

Recent studies have shown that human basophils, like mast cells, generate interleukin (IL)-4 following immunological activation and may thus participate in late-phase allergic and inflammatory processes. Here, we report the capacity of human basophils to release IL-13 within 24 h following stimulation with anti-IgE. Additionally, in 14 out of 31 experiments, we observed that basophils rapidly release performed IL-4 within 5-10 min, as well as newly generated IL-4, which was released 4 h following stimulation of the cells with anti-IgE. In contrast to the biphasic release of IL-4 from the cells, no preformed IL-13 was detected at earlier times (5-30 min). Preformed IL-4 and IL-4 and IL-13 generated de novo were also released after stimulation of the cells with IL-3; an enhanced production of these cytokines was observed using a combination of IL-3 and anti-IgE. We conclude from these data that, by releasing performed IL-4 and IL-4 and IL-13 generated de novo, human basophils may be centrally involved in the orchestration of allergic inflammation by providing a trigger to IL-4-mediated T helper 2 lymphocyte activation, B cell IgE switching, and increased vascular adhesion molecule expression.

Antibodies, Anti-Idiotypic↗

Eotaxin is a potent chemotaxin for human basophils.

We studied the effect of eotaxin, a novel eosinophil-active CC chemokine with high target cell specificity, on human basophils. Eotaxin induced higher levels of chemotactic response with a lower ED50 compared with RANTES in basophils; half-maximal migration occurred at a concentration of approximately 3 nM. On the other hand, it exerted only a marginal effect on either histamine release or leukotriene C4 generation. In addition, nested PCR amplification experiments revealed the expression of CC CKR3, a putative receptor for eotaxin, on basophils. Since accumulation of both basophils and eosinophils is an important aspect of allergic inflammation, eotaxin potentially plays a pathogenic role in allergic disorders by inducing migration of both of these cell types.

Basophils↗