Characteristics of histamine release from cultured human mast cells

BACKGROUND

The mast cell is one of the important cells in the pathogenesis of allergic disorders. However, isolating human mast cells is a laborious procedure. Recently, cultured human mast cells raised from umbilical cord blood cells have become available. It is necessary to examine whether these cells are useful in investigating the role of mast cells in human diseases.

OBJECTIVE

The phenotype of mast cells depends on their anatomical sites. To examine which phenotype of mast cells these cultured mast cells most closely resemble, their ability to release was investigated.

METHODS

The mast cells were raised from human umbilical cord blood cells in the presence of stem cell factor and interleukin-6. To determine the mast cell subtypes, the mast cells were immunocytochemically stained for tryptase and chymase. The cultured mast cells were then stimulated with various secretagogues, and histamine release was measured by a fluorometric technique using high-performance liquid chromatography.

RESULTS

The immunocytochemical staining for mast cell proteases revealed that virtually all cells contained tryptase, the definitive marker of mast cells, and that about a quarter of the cells contained chymase. Anti-IgE effectively stimulated these mast cells to release histamine in a dose-dependent, time-dependent manner. The release was completed in about 30 min. One of the non-specific stimuli, calcium ionophore A23187, also induced histamine release in a dose-dependent, time-dependent manner. In contrast, compound 48/80 and substance P failed to induce histamine release from these cells.

CONCLUSION

Cultured human mast cells resemble lung mast cells in their ability to release histamine. They will help in studying the functional properties of human mast cells and may contribute to clarifying the pathophysiology of human allergic diseases.

[The role of cytokines and cell adhesion molecules in allergic inflammation]

The mechanisms of late phase allergic reaction (LAR) have been investigated by many researchers in the past decade, since LAR was recognized clinically to be more important than early phase allergic reaction (EAR). The selective eosinophil recruitment in LAR can be explained by the hypothesis of the cascade of cytokines and adhesion molecules. Since cytokines were initially identified as the factors derived from activated T cells, T cells were thought to play an important role in the LAR in the late 1980s. In 1989, murine mast cells were reported to produce many cytokines following activation through Fc epsilon R I. The current topic is to clarify which cell type mainly induce LAR either CD4+ T cells or mast cells.

Relationship between histamine release and leukotrienes production from human basophils derived from atopic dermatitis donors

Basophils are known to release histamine and to produce leukotrienes (LTs) following both IgE-dependent and -independent stimuli. Although there exist a few reports which examined the relationship between histamine release and LTs production, their conclusions were not always in agreement with each other. In the present study, we examined the relationship between histamine release and LTs production from basophils in the presence or absence of 1 ng/ml of interleukin-3 (IL-3). Normal basophils released a smaller amount of histamine and LTs than atopic determatitis (AD) basophils, when basophils were stimulated with an optimal concentration of anti-IgE antibody. When we examined the relationship of histamine release and LTs production from AD donors induced through Fc epsilon RI, we found a significant exponential correlation between these two mediators (R2 = 0.58 in the absence of IL-3, R2 = 0.83 in the presence of IL-3). Although IL-3 enhanced both histamine release and LTs production from AD donors, the relationship between these two mediators was not affected. In conclusion, there was an exponential correlation between histamine release and LTs production from AD basophils, which was not affected by the pretreatment with IL-3.

Study of liver function in infants with atopic dermatitis using the 13C-methacetin breath test

Serum glutamic-oxaloacetic transaminase (GOT) levels were determined in 214 infants (133 males and 81 females) with atopic dermatitis during their first visit to the Department of Allergy, National Children's Hospital, Tokyo, Japan. Compared with the normal hospital range, their levels were found to be significantly higher, a tendency which was more conspicuous in lower age groups. We carried out a 13C-methacetin breath test (MBT), administering the stable-isotope-labeled compound to 11 children with higher serum GOT values and 5 within the normal range to investigate hepatic metabolism of methacetin in infants with atopic dermatitis. 13C-methacetin was given orally, and the 13CO2 level in the breath was determined immediately before and after administration, by mass spectrometry. Compared to the normal controls, the atopic infants demonstrated significantly lower 13CO2 peak excretion and delayed peak time. The clearance rate of 13CO2 was also decreased. These results suggest some relationship between atopic dermatitis and liver function in infants.

Characterization of cord-blood-derived human mast cells cultured in the presence of Steel factor and interleukin-6

We generated > 10(7) mast cells by culturing 10(7) cord blood mononuclear cells for > 10 weeks in the presence of Steel factor, interleukin-6 and prostaglandin E2. 99% of the cultured cells had tryptase-positive granules, while 18% had chymase-positive granules. Cultured mast cells contained 3.6 micrograms histamine and 3.5 micrograms tryptase per 10(6) cells. Cells sensitized with 1 microgram/ml human IgE released 58.5% histamine and 1.55 ng tumor necrosis factor (TNF)-alpha per 10(6) cells when challenged with 1 microgram/ml antihuman IgE, whereas the control cells spontaneously released 3.7% histamine and 0.18 ng TNF-alpha. Analysis for surface antigens revealed that cultured mast cells expressed the following CD molecules: 9, 13, 14, 29, 33, 38, 43, 44, 45RA, 45RB, 46, 47, 48, 49d, 50, 51, 53, 54, 55, 58, 59, 60, 61 and 117 (c-Kit). Taken together, these cultured cells seem to be functionally mature mast cells.

Pharmacokinetics and pharmacodynamics of the tulobuterol patch, HN-078, in childhood asthma

BACKGROUND

Recently, a novel percutaneous adhesive tulobuterol preparation, HN-078, has been developed and tests using healthy adult subjects have indicated it to be effective for controlling exacerbations early in the morning if applied at bedtime. In children, percutaneous application is very important to eliminate side effects, including abdominal pain and appetite loss.

OBJECTIVE

We report the pharmacokinetics and pharmacodynamics of tulobuterol patch, HN-078, in the treatment of childhood asthma.

METHODS

Single applications of HN-078 were applied transdermally in six children with asthma who had been admitted to a hospital. Subjects weighing less than 30 kg received 1 mg of tulobuterol while subjects weighing 30 kg or above received 2 mg on the chest for 24 hours. Serum tulobuterol levels and peak expiratory flow rate were determined before and after each application.

RESULTS

Cmax of tulobuterol was determined to be 1.33 +/- 0.21 ng/mL, Tmax was 14.0 +/- 2.0 hours, and AUCO-t was 27.1 +/- 4.2 ng.hr/mL. These pharmacokinetic parameters per body surface area of children were nearly equivalent to those of adults obtained in other studies. Peak expiratory flow rate values obtained after application of HN-078 significantly increased in comparison to those obtained before application. No significant changes were observed in pulse rate or blood pressure, and no side effects were found with regard to the subjective symptoms and skin conditions.

CONCLUSIONS

These results suggest that the patch formulation of tulobuterol, HN-078, will be very useful for the treatment of pediatric asthma. It is especially significant that no side effects were observed.

[Adrenocortical function in children with near fatal asthma]

The adrenal function of children with near fatal asthma was evaluated by a modified rapid ACTH test. The rapid ACTH tests, which were performed within six months of each life-threatening asthmatic episode, showed extremely low responsiveness. The response in the subjects was significantly lower than that of patients who had received high dose of corticosteroid therapy. It was suggested that the adrenocortical function of children with near fatal asthma had been already suppressed and that adrenal suppression could easily occur in such patients. We advocate the following measures: (1) environmental control, education of patients and their families, physical training accurate medication should be supplied to reduce the use of corticosteroids, (2) sufficient doses of corticosteroids should, however be given to patients with acute exacerbation, (3) not only lung function tests or allergic examinations, but also adrenocortical function tests should be performed on severe asthmatic patients.

Eosinophil transendothelial migration induced by cytokines. III. Effect of the chemokine RANTES

Selective eosinophil recruitment occurs after experimental Ag challenge and in tissue sites of allergic diseases. The mechanisms of selective eosinophil migration are still unknown. In our study, we examined the ability of chemokines to induce transendothelial migration (TEM) of eosinophils in vitro. Among the chemokines tested, only RANTES induced eosinophil TEM. RANTES failed to induce TEM of neutrophils. Interestingly, IL-8 induced neutrophil TEM and had no effect on eosinophil TEM. RANTES-induced TEM was concentration-dependent and was inhibited by Abs directed against the beta 2 integrin CD18. When IL-1-activated endothelial cells were utilized, RANTES-induced TEM also involved the eosinophil beta 1 integrin VLA-4. RANTES did not increase eosinophil adhesion to either resting or IL-1-activated endothelial cells, nor did the chemokine increase CD11b or decrease L-selectin expression. A gradient of RANTES appears to be required for eosinophil TEM. Pre-exposure of eosinophils to IL-5 dramatically potentiated the TEM response to RANTES. These findings suggest that the chemokine RANTES is a potent and selective inducer of eosinophil TEM. Because RANTES appears to be produced in vivo during allergic reactions or in allergic diseases, we speculate that these findings may have some direct relevance to the mechanism of selective eosinophil recruitment in vivo in humans.

Eosinophil transendothelial migration induced by cytokines. III. Effect of the chemokine RANTES

Selective eosinophil recruitment occurs after experimental Ag challenge and in tissue sites of allergic diseases. The mechanisms of selective eosinophil migration are still unknown. In our study, we examined the ability of chemokines to induce transendothelial migration (TEM) of eosinophils in vitro. Among the chemokines tested, only RANTES induced eosinophil TEM. RANTES failed to induce TEM of neutrophils. Interestingly, IL-8 induced neutrophil TEM and had no effect on eosinophil TEM. RANTES-induced TEM was concentration-dependent and was inhibited by Abs directed against the beta 2 integrin CD18. When IL-1-activated endothelial cells were utilized, RANTES-induced TEM also involved the eosinophil beta 1 integrin VLA-4. RANTES did not increase eosinophil adhesion to either resting or IL-1-activated endothelial cells, nor did the chemokine increase CD11b or decrease L-selectin expression. A gradient of RANTES appears to be required for eosinophil TEM. Pre-exposure of eosinophils to IL-5 dramatically potentiated the TEM response to RANTES. These findings suggest that the chemokine RANTES is a potent and selective inducer of eosinophil TEM. Because RANTES appears to be produced in vivo during allergic reactions or in allergic diseases, we speculate that these findings may have some direct relevance to the mechanism of selective eosinophil recruitment in vivo in humans.

Eosinophil transendothelial migration induced by cytokines. II. Potentiation of eosinophil transendothelial migration by eosinophil-active cytokines

Activation of HUVEC monolayers by IL-1 beta or TNF-alpha induces migration of eosinophils across the endothelial monolayer (i.e., transendothelial migration) in vitro. In the present study, we demonstrate that culture of freshly isolated eosinophils in the presence of IL-5 for 24 to 48 h before use in the assay dramatically potentiated CD18-dependent eosinophil transendothelial migration through unstimulated endothelial monolayers. Granulocyte macrophage (GM)-CSF induced eosinophil transendothelial migration but did not induce neutrophil transendothelial migration. When IL-1 beta-activated endothelial cells were used, GM-CSF, IL-3, or IL-5 caused only modest potentiation of eosinophil transendothelial migration. Since activated endothelial cells are known to produce GM-CSF, we hypothesized that endothelial-derived GM-CSF might play a role in the process of IL-1 beta-induced eosinophil transendothelial migration. IL-1 beta-activated endothelial monolayers grown on the permeable supports produced 0.3 +/- 0.1 ng/ml of GM-CSF during a 4-h incubation and neutralizing Ab against GM-CSF inhibited eosinophil transendothelial migration by 48%, suggesting that endothelial-derived GM-CSF may participate in the response. Eosinophils purified from bronchoalveolar lavage 18 to 20 h after experimental Ag challenge in the lungs of allergic volunteers showed enhanced transendothelial migration, indicating that the cells may have undergone cytokine activation in vivo. Eosinophil-active cytokines may contribute to the preferential accumulation of eosinophils in vivo in part via potentiation of eosinophil transendothelial migration.

Eosinophil transendothelial migration induced by cytokines. II. Potentiation of eosinophil transendothelial migration by eosinophil-active cytokines

Activation of HUVEC monolayers by IL-1 beta or TNF-alpha induces migration of eosinophils across the endothelial monolayer (i.e., transendothelial migration) in vitro. In the present study, we demonstrate that culture of freshly isolated eosinophils in the presence of IL-5 for 24 to 48 h before use in the assay dramatically potentiated CD18-dependent eosinophil transendothelial migration through unstimulated endothelial monolayers. Granulocyte macrophage (GM)-CSF induced eosinophil transendothelial migration but did not induce neutrophil transendothelial migration. When IL-1 beta-activated endothelial cells were used, GM-CSF, IL-3, or IL-5 caused only modest potentiation of eosinophil transendothelial migration. Since activated endothelial cells are known to produce GM-CSF, we hypothesized that endothelial-derived GM-CSF might play a role in the process of IL-1 beta-induced eosinophil transendothelial migration. IL-1 beta-activated endothelial monolayers grown on the permeable supports produced 0.3 +/- 0.1 ng/ml of GM-CSF during a 4-h incubation and neutralizing Ab against GM-CSF inhibited eosinophil transendothelial migration by 48%, suggesting that endothelial-derived GM-CSF may participate in the response. Eosinophils purified from bronchoalveolar lavage 18 to 20 h after experimental Ag challenge in the lungs of allergic volunteers showed enhanced transendothelial migration, indicating that the cells may have undergone cytokine activation in vivo. Eosinophil-active cytokines may contribute to the preferential accumulation of eosinophils in vivo in part via potentiation of eosinophil transendothelial migration.

Growth in methylcellulose of human mast cells in hematopoietic colonies stimulated by steel factor, a c-kit ligand

We examined the effect of Steel factor (SLF) on the development of human mast cells in hematopoietic colonies from cord blood mononuclear cells in methylcellulose culture. When cord blood cells were cultured for 3 weeks, SLF increased the cellular tryptase levels detected in total cultured cells. It also stimulated the formation of small-cell colonies consisting mainly of polymorphonuclear granulocytes and immature blastoid cells in a concentration-dependent manner but not the formation of colonies consisting of large macrophagic cells. A low percentage of tryptase-positive mast-cell-like cells was found in 39 out of 100 granulocyte/blastoid cell colonies. Four of the 100 colonies contained 10-20% tryptase-positive cells, but we failed to observe colonies consisting of > 20% of tryptase-positive cells. These results suggest that the effect of SLF on mast cell growth is brought on by stimulating the growth of primitive hematopoietic progenitors.

Expression of a functional laminin receptor (alpha 6 beta 1, very late activation antigen-6) on human eosinophils

The mechanisms responsible for the accumulation of eosinophils at sites of allergic and other inflammatory reactions are unknown, but recent studies have implicated both eosinophil and endothelial adhesion molecules in this process. However, less well studied have been the adhesive interactions between eosinophils and the subendothelial basement membrane and interstitial connective tissues. To test the hypothesis that eosinophils might interact with extracellular matrix proteins, we analyzed purified human eosinophils for the expression and function of various beta 1 integrins. Using indirect immunofluorescence and flow cytometry, purified eosinophils from mildly allergic donors were found to consistently express the integrin subunits beta 1 (CD29), alpha 4 (CD49d, very late activation antigen [VLA]-4 alpha), and alpha 6 (CD49f, VLA-6 alpha). No significant expression of the alpha 1, alpha 2, alpha 3, alpha 5, or beta 4 subunits was detected. Platelet contamination of the eosinophil preparations was excluded by light microscopy and by the inability to detect expression of platelet glycoproteins alpha v, CD41b, and CD42b. Immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of eosinophils confirmed the expression of cell-surface beta 1, alpha 4, and alpha 6. Furthermore, eosinophils purified from allergic donors were shown to adhere to plate-bound laminin, but not to type 1 or type 4 collagen. Adhesion to laminin was concentration-dependent, required divalent cations, and was completely and specifically inhibited by the anti-alpha 6 monoclonal antibody (MoAb) GoH3 and by the anti-beta 1 MoAb 33B6. Interestingly, the anti-beta 1 MoAb 18D3 (which like 33B6 blocks eosinophil binding to VCAM-1) did not inhibit eosinophil adhesion to laminin, suggesting that there are functionally distinct epitopes on the beta 1 subunit. Eosinophils purified from 4 healthy, nonallergic donors also showed alpha 6-dependent adhesion to laminin, although these cells adhered less well. These studies establish the expression of alpha 6 beta 1 on human eosinophils and document its function as a laminin receptor. Interaction of eosinophil alpha 6 beta 1 with laminin, eg, in basement membranes, may contribute to the localization of these cells at inflammatory sites in vivo.

Effect of inhaled beclomethasone dipropionate on bronchial responsiveness in patients with asthma

We investigated the effect of 300 micrograms of inhaled beclomethasone dipropionate (BDP) daily on bronchial responsiveness to methacholine and pulmonary function of 22 subjects with asthma in a single-blind, crossover study. The severity of bronchial hyperresponsiveness lessened significantly during treatment with BDP (P < .01). No significant changes occurred in FEV1 or in the control value of airway conductance. We conclude that a 300-micrograms total daily dose of BDP is an efficacious treatment for patients with asthma. Because suppression of adrenal function and systemic adverse effects can occur in asthmatic patients treated with inhaled corticosteroids, especially children, long-term treatment with inhaled steroids should employ minimal daily doses necessary.

Eosinophil transendothelial migration induced by cytokines. I. Role of endothelial and eosinophil adhesion molecules in IL-1 beta-induced transendothelial migration

IL-1 beta promotes adhesiveness in human umbilical vein endothelial cells (HuVEC) for eosinophils through expression of adhesion molecules including intercellular adhesion molecules-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1). Using an in vitro endothelial monolayer system, we examined whether IL-1 beta or TNF-alpha can promote eosinophil transendothelial migration. We also evaluated the contributions of ICAM-1, E-selectin, VCAM-1, leukocyte adhesion complex (CD11/18), and very late Ag-4 (CD11b/18) (VLA-4) in this process using blocking mAb, and determined the changes in expression of CD11b and L-selectin on eosinophils that had undergone transmigration. IL-1 beta and TNF-alpha treatment of HuVEC (4 h, 5 ng/ml) induced significant transendothelial migration of eosinophils (a 4.1 +/- 0.4-fold (IL-1 beta) and 2.0 +/- 0.9-fold (TNF-alpha) increase from the spontaneous value of 3.2 +/- 0.3%). Increased CD11b expression and shedding of L-selectin were observed on eosinophils following IL-1 beta-induced eosinophil transendothelial migration. Studies with mAb revealed that blockade of either ICAM-1 or CD11/18 inhibited transmigration, while antibodies against VCAM-1 and VLA-4 had no inhibitory effect. Among antibodies which block beta 2 integrins, anti-CD18 mAb had the best inhibitory effect (88% inhibition). The combined inhibitory effect of anti-CD11a mAb and anti-CD11b mAb was roughly equal to that of anti-CD18, although anti-CD11a (31% inhibition) and anti-CD11b (52% inhibition) were less effective individually. Anti-ICAM-1 by itself inhibited IL-1 beta-induced eosinophil transendothelial migration (24% inhibition) whereas neither anti-E-selectin nor anti-VCAM-1 were effective inhibitors. Interestingly, the combination of anti-E-selectin and anti-VCAM-1 with anti-ICAM-1 inhibited IL-1 beta-induced eosinophil transendothelial migration significantly better (53% inhibition) than anti-ICAM-1 alone. These results suggest that although the initial attachment of eosinophils to IL-1 beta-activated endothelial cells involves VCAM-1, E-selectin, and ICAM-1, the subsequent transendothelial migration process relies heavily on ICAM-1 and CD11/18. Finally, the changes that eosinophils have been observed to undergo during infiltration in vivo, namely increased expression of CD11/18 and shedding of L-selectin, appear to take place as a direct result of the interaction between eosinophils and endothelial cells.

Eosinophil transendothelial migration induced by cytokines. I. Role of endothelial and eosinophil adhesion molecules in IL-1 beta-induced transendothelial migration

IL-1 beta promotes adhesiveness in human umbilical vein endothelial cells (HuVEC) for eosinophils through expression of adhesion molecules including intercellular adhesion molecules-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1). Using an in vitro endothelial monolayer system, we examined whether IL-1 beta or TNF-alpha can promote eosinophil transendothelial migration. We also evaluated the contributions of ICAM-1, E-selectin, VCAM-1, leukocyte adhesion complex (CD11/18), and very late Ag-4 (CD11b/18) (VLA-4) in this process using blocking mAb, and determined the changes in expression of CD11b and L-selectin on eosinophils that had undergone transmigration. IL-1 beta and TNF-alpha treatment of HuVEC (4 h, 5 ng/ml) induced significant transendothelial migration of eosinophils (a 4.1 +/- 0.4-fold (IL-1 beta) and 2.0 +/- 0.9-fold (TNF-alpha) increase from the spontaneous value of 3.2 +/- 0.3%). Increased CD11b expression and shedding of L-selectin were observed on eosinophils following IL-1 beta-induced eosinophil transendothelial migration. Studies with mAb revealed that blockade of either ICAM-1 or CD11/18 inhibited transmigration, while antibodies against VCAM-1 and VLA-4 had no inhibitory effect. Among antibodies which block beta 2 integrins, anti-CD18 mAb had the best inhibitory effect (88% inhibition). The combined inhibitory effect of anti-CD11a mAb and anti-CD11b mAb was roughly equal to that of anti-CD18, although anti-CD11a (31% inhibition) and anti-CD11b (52% inhibition) were less effective individually. Anti-ICAM-1 by itself inhibited IL-1 beta-induced eosinophil transendothelial migration (24% inhibition) whereas neither anti-E-selectin nor anti-VCAM-1 were effective inhibitors. Interestingly, the combination of anti-E-selectin and anti-VCAM-1 with anti-ICAM-1 inhibited IL-1 beta-induced eosinophil transendothelial migration significantly better (53% inhibition) than anti-ICAM-1 alone. These results suggest that although the initial attachment of eosinophils to IL-1 beta-activated endothelial cells involves VCAM-1, E-selectin, and ICAM-1, the subsequent transendothelial migration process relies heavily on ICAM-1 and CD11/18. Finally, the changes that eosinophils have been observed to undergo during infiltration in vivo, namely increased expression of CD11/18 and shedding of L-selectin, appear to take place as a direct result of the interaction between eosinophils and endothelial cells.

[The effect of sustained-release theophylline granules in the inhibition of exercise-induced asthma]

We studied the protective effect of sustained-release theophylline granules on early or late response in exercise-induced asthma (EIA) in 16 patients ranging in age from 7 to 18 years. A standardized exercise test was examined 2 hours after administration of theophylline granules on one day and after no medication on another day. On both days, the lung functions and the serum theophylline and cortisol concentrations of the patients were examined before exercise and over a period of 8 hours after exercise. On days without medication, early response was seen in 16 patients and late response in 6. On days with medication, the theophylline granules inhibited early response in 13 of the 16 patients and late response in 5 of the 6 patients. This suggests that theophylline preparation is a useful drug for inhibiting the dual responses of EIA.

Interleukin 4-mediated induction of CD4+/CD8+ T cells during infancy

Neonatal human CD4+ T cells will co-express CD8 on their surface following short-term culture with interleukin 4 (IL-4). Adult T cells do not respond in this manner. In this study we examine this phenomenon as a function of age and determine that IL-4 responsiveness decreases with time to approach adult levels at about 2 years. This phenomenon may be relevant to the documented ability of neonatal CD4+ T cells to function as suppressors.

The stimuli releasing histamine from murine bone marrow-derived mast cells. 2. Mechanisms involved in histamine release induced by extracellular ATP and its metabolites

Extracellular ATP stimulated histamine release and generation of leukotrience C4 (LTC4) accompanied with the formation of inositol phosphates and a rapid increase in intracellular Ca2+ ([Ca2+]i) in mouse bone marrow-derived cultured mast cells (BMMC). The rank order of histamine-releasing potency of ATP and its metabolites is ATP greater than ADP greater than AMP greater than adenosine. Nonhydrolyzable ATP analog, adenosine-5'-O-[2-thiotriphosphate] (ATP-S) released more histamine from the cells than ATP. On the other hand, simultaneous addition of adenosine analogues at micromolar concentrations potentiated histamine release from the cells induced by ATP (50 microM) or DNP-HSA antigen (0.1 ng/ml) in the following rank order: adenosine greater than AMP much greater than ADP = ATP. Histamine release potentiated by adenosine was blocked by the treatment with pertussis toxin, whereas histamine release induced by ATP was not affected by the toxin, suggesting that extracellular ATP stimulate histamine release from BMMC probably via mechanisms independent of the potentiation of histamine release induced by adenosine.

Changes in filament actin accompanying IgE-dependent and -independent histamine release from IL-3-dependent cultured human basophils

When cord blood mononuclear cells were cultured in the presence of rhIL-3 for 5 weeks or more, 40-90% of cultured cells became morphologically mature basophils. We analyzed the kinetics of histamine release, changes in filament actin (F-actin), and movement of intracellular Ca2+ ([Ca2+]i) induced by IgE-dependent (anti-IgE) and -independent (fMLP) stimuli in these cultured basophils. Anti-IgE and fMLP released 24.5 +/- 5.4% and 14.5 +/- 4.5% histamine from the cells, respectively. Anti-IgE caused actin polymerization with a peak response at 15 min, which began much later than the elevation of [Ca2+]i. In contrast to anti-IgE stimulation, fMLP induced rapid actin polymerization with a peak response at 30 s in correlation with kinetics of histamine release. Our results indicate that cord blood-derived cultured basophils show similar cell functions to mature basophils, and are useful models with which to investigate the mechanisms of degranulation, specifically when a large amount of highly purified cells are required.

Extracellular ATP stimulates interleukin-dependent cultured mast cells and eosinophils through calcium mobilization

We examined the effect of ATP and related nucleotides on the changes in intracellular calcium ([Ca2+]i) in murine bone marrow-derived mast cells (BMMC) and human cord blood-derived eosinophils (EO) cultured in the presence of interleukins. ATP, ADP and AMP released a substantial amount of histamine and leukotriene C4 from BMMC, and EO showed locomotive activity in response to ATP, ADP and GTP. These reactions were accompanied with an increase in [Ca2+]i in BMMC and in EO. The rise in [Ca2+]i in BMMC induced by ATP or antigen at optimal concentrations was inclined to be persisting. On the other hand, these nucleotides induced a rapid and transient rise in [Ca2+]i in EO. Purified human peripheral EO also exhibited locomotive activity and an increase in [Ca2+]i in response to ATP. These results indicate that extracellular ATP activates interleukin-dependent cultured mast cells and EO through Ca2+ mobilization, and suggest that ATP, which is known to be released from activated platelets or autonomic nerves, may stimulate in vivo counterparts of these cultured inflammatory cells.

Interleukin 4 induces CD4+/CD8- to CD8+/CD4- transformation of human neonatal T cells by way of a double positive intermediate

We have determined that IL-4 induces the generation of CD4+/CD8+ T cells in cultures of neonatal lymphocytes. Sorting, positive, and negative selection experiments indicate that these cells arise from a subpopulation of CD4+/CD8- cells present in the neonate but not in the adult. We have further determined that these IL-4 generated "double positive" cells further differentiate to express only the CD8 marker. Our findings suggest an undescribed and dramatic role for IL-4 in T cell differentiation.

Chemical mediators in hypersensitivity reactions

The study of chemical mediators is essential in clarifying the mechanism of hypersensitivity reactions. Recent advances in this field have been made particularly with the arachidonic acid metabolites, several of which strongly contract smooth muscle, attract granulocytes to inflammatory foci and lead to increased vascular permeability. These functions play a crucial role in allergic reactions. Furthermore these mediators might work to modulate the intracellular network which mediates the complicated inflammatory process of hypersensitivity reactions.

Platelet-activating factor-induced activation and cytoskeletal change in cultured eosinophils

The culture of mononuclear umbilical cord blood cells with low concentrations of interleukin-3 (IL-3) and interleukin-5 (IL-5) for 3 weeks or more results in the consistent production of large numbers of eosinophils. Density distribution analysis and electron microscopic analysis revealed the characteristics of cultured eosinophils to be partially different from peripheral eosinophils. In modified Boyden chamber studies, cultured eosinophils exhibited locomotive activity in response to platelet-activating factor (PAF), with a peak response at 10(-6) M, but not to N-formyl-L-methionyl-L-leucyl-L-phenylalanine. PAF-induced changes in intracellular calcium concentrations in peripheral eosinophils and cultured eosinophils were similar. PAF-induced actin polymerization was observed in cultured eosinophils for the first 30 s followed by depolymerization for the next 10 min. These results suggest that cultured eosinophils respond to PAF in a manner analogous to peripheral eosinophils, and will be useful for in vitro studies.

Human cord blood lymphocytes do not simultaneously express CD4 and CD8 cell surface markers

Several authors have reported finding significant numbers of immature T lymphocytes of the CD4/CD8 'double positive' phenotype in human cord blood. We have studied over 30 cord blood samples using directly conjugated reagents and have failed to detect such cells in any of the samples. Differences in staining methodologies that may account for this discrepancy are discussed.

Effects of human recombinant interleukin 5 and 3 on the differentiation of cord blood-derived eosinophils and basophils

When mononuclear cells from umbilical-cord blood were cultured for 3 weeks, low concentrations of interleukin 3 supported the preferential growth of basophils, with eosinophils comprising a smaller proportion. These basophils contained 0.15-0.3 microgram histamine per 10(6) cells, and released histamine by the IgE-dependent and -independent stimuli. Interleukin 5 increased the number and proportion of eosinophils in a dose-dependent manner without affecting the proliferation of other cell types in the interleukin 3-supplemented cultures. These cultured eosinophils could be activated by platelet-activating factor.