Chest ACCP Education Calendar
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Guest Access | Sign In via User Name/Password
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Article Archive
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (6)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ho, C.-Y.
Right arrow Articles by Lam, C. W.-K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ho, C.-Y.
Right arrow Articles by Lam, C. W.-K.
(Chest. 2002;122:1751-1758.)
© 2002 American College of Chest Physicians

Apoptosis and B-Cell Lymphoma-2 of Peripheral Blood T Lymphocytes and Soluble Fas in Patients With Allergic Asthma*

Cheong-Yip Ho, PhD; Chun-Kwok Wong, PhD; Fanny Wai-San Ko, MD; Christopher Hok-Sum Chan, MD, FCCP; Alice Sheng-Sheng Ho, MD; David Shu-Cheong Hui, MD, FCCP and Christopher Wai-Kei Lam, PhD

* From the Departments of Chemical Pathology (Drs. C.-Y. Ho, Wong, and Lam) and Medicine and Therapeutics (Drs. Ko and Hui), The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; and the Department of Medicine (Drs. Chan and A.S.-S. Ho), Alice Ho Miu Ling Nethersole Hospital, Tai Po, Hong Kong.

Correspondence to: Christopher Wai-Kei Lam, PhD, Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong: e-mail: waikeilam{at}cuhk.edu.hk


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Study objectives: The dysregulation of apoptosis and the expression of apoptosis-related molecules of allergen-reactive T lymphocytes have been suggested to play a key role in the development and maintenance of the inflammatory reactions in allergic asthma. Glucocorticoids are effective drugs for treating allergic inflammation. In this study, we investigated the effect of dexamethasone (DEX) on the apoptosis and B-cell lymphoma (Bcl)-2 expression of peripheral blood T lymphocytes as well as the soluble form of Fas (sFas) in allergic asthmatic patients.

Methods: Peripheral blood lymphocytes from 41 allergic asthmatic patients and 30 age-matched and sex-matched control subjects were treated with 0.1 and 1 µM DEX. The percentages of apoptosis and expression of the Bcl-2 molecule in T lymphocytes were assessed by flow cytometry. The plasma concentration of sFas was measured using the enzyme-linked immunosorbent assay.

Results: DEX (0.1 and 1 µM) could induce the apoptosis of T lymphocytes from allergic asthmatic patients and control subjects in a dose-dependent manner in vitro. The apoptotic susceptibility of T lymphocytes to DEX and the plasma sFas concentration were significantly higher in allergic asthmatics. The ex vivo expression of Bcl-2 was significantly lower in the T lymphocytes of asthmatic patients than in those of the control subjects. However, DEX did not have any significant effect on the expression of Bcl-2 in vitro.

Conclusions: The T lymphocytes of asthmatic patients have higher apoptotic susceptibility to DEX treatment in vitro and a lower expression of the Bcl-2 molecule.

Key Words: allergic asthma • apoptosis • B-cell lymphoma-2 • dexamethasone • sFas • T lymphocytes


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Allergic asthma is a complex disease that is characterized by intermittent reversible airway obstruction, chronic airway inflammation, bronchial overreactivity, and infiltration of lymphocytes and eosinophils into the airway submucosa.1 In allergic inflammation, lymphocytes and eosinophils are known to accumulate at the site of inflammation partly because of their prolonged survival.2 The overactivation of T lymphocytes in the peripheral blood and airway tissues has been shown to be an invariant feature of asthma,3 4 5 and altered apoptotic potential seems to be crucial in promoting the survival of activated T cells. After responding to foreign antigens or allergens, the Fas-dependent pathway of T-cell death is linked to T-cell receptor-dependent apoptosis and the subsequent elimination of activated T cells.6 A 1999 study reported a selective resistance of activated T cells to undergo Fas-mediated apoptosis in asthmatic patients and suggested that the increased number of activated T cells might have been due to their decreased rate of cell death.7 Such findings may provide the initial evidence for the defect in apoptosis of lymphocytes in the pathogenesis of asthma.

Glucocorticoids (GCs) are effective drugs that are currently available for treating allergic inflammation in asthmatic patients. They directly inhibit the prolonged survival of various inflammatory cells, including lymphocytes and eosinophils, by inducing apoptosis and, indirectly, by suppressing the expression of multiple proinflammatory genes, including interleukin-3, interleukin-5, granulocyte- macrophage colony-stimulating factor, inflammatory enzymes, adhesion molecules, and inflammatory mediator receptors.8 Dexamethasone (DEX), one of the synthetic GCs, is a potent apoptosis inducer in inflammatory cells. One study9 has found that DEX can induce significantly greater apoptosis in peripheral T cells in patients with asthma than in healthy control subjects, and can reduce the number of allergen-specific T cells through apoptosis. However, another group10 has demonstrated that DEX can inhibit the apoptosis of lung epithelial cells induced by interferon-{gamma} and Fas. Therefore, the exact mechanisms of effectiveness of GCs are not fully clarified.

Fas (APO-1 or CD95) is a cell surface glycoprotein that is expressed on rapidly proliferating cells and is strongly up-regulated on activated lymphocytes.11 Fas antigen has been shown to be responsible for the apoptosis of lymphocytes by crosslinking with its own ligand (Fas-ligand).12 Kato et al13 showed that serum levels of soluble Fas (sFas) during the attack phase in patients with allergic rhinitis were significantly lower than those in healthy individuals. In contrast, serum sFas levels in patients with bronchial asthma during the attack phase were higher, suggesting a different pathogenesis for allergic rhinitis and bronchial asthma at the apoptosis-linked step.

The up-regulation of the B-cell lymphoma (Bcl)-2 molecule has been shown to inhibit the apoptotic death of peripheral blood lymphocytes in patients with systemic lupus erythematosus.14 Previous studies15 have revealed that Bcl-2-positive T cells in asthmatic patients are more abundant than in control subjects, showing a positive correlation between the number of T lymphocytes and the severity of disease. However, another group has demonstrated that the numbers of Bcl-2-positive T cells are similar in untreated and steroid-treated asthmatic patients and control subjects.16 Since the exact regulatory mechanisms of the apoptosis of peripheral T cells in patients with asthma have not been well-elucidated, the present study was undertaken to investigate the apoptosis of peripheral blood T lymphocytes in allergic asthmatic patients receiving DEX treatment in vitro and the expression of apoptosis-related molecules Fas and Bcl-2.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Study Populations and Blood Sample Preparation
Forty-one Chinese asthmatic patients were recruited at the asthma clinics of the Prince of Wales Hospital and Alice Ho Miu Ling Nethersole Hospital in Hong Kong. A diagnosis of asthma was based on the guidelines proposed by the American Thoracic Society.17 At the time of participation in the study, all asthmatic patients had undergone spirometric assessment (model S; Vitalograph; Buckingham, UK) to determine their lung function levels according to the American Thoracic Society standards.18 FEV1, FVC, and the FEV1/FVC ratio were measured before and 15 min after the inhalation of salbutamol (Glaxo Operations Ltd; Greenford, UK). The results were compared with the local predicted age-matched and sex-matched values.19 The severity of asthma in these patients was assessed according to the Global Initiative for Asthma guidelines.20 21 All of studied asthmatic patients were receiving therapy with short-acting bronchodilators as needed. They were also receiving treatment with regular inhaled steroids such as beclomethasone dipropionate (Becloforte; Glaxo Wellcome; Research Triangle Park, NC) or budesonide (Pulmicort; AstraZeneca; London, UK). All patients and control subjects had not received oral steroids or changed asthma medications in the 4 weeks prior to recruitment for the study. They were also not receiving theophylline, long-acting ß2-agonists, or antileukotriene therapy. Thirty age-matched and sex-matched healthy Chinese volunteers were recruited as healthy control subjects. Both atopic and nonatopic control subjects were free from asthmatic symptoms. The occurrence of allergic diseases in these subjects was excluded using a detailed questionnaire. All subjects were nonsmokers and had been free from upper respiratory tract infections for the 4 weeks preceding entry into the study. Twenty milliliters of heparinized venous peripheral blood was collected from each patient and control subject. An aliquot of whole blood from each subject was processed immediately for analysis of the Bcl-2 expression. Plasma samples were preserved at -70°C for subsequent assays. The above protocol was approved by the Clinical Research Ethics Committee of the Chinese University of Hong Kong, and informed consent was obtained from all participants.

Plasma Allergen-Specific IgE, Eosinophil Cationic Protein, and sFas
The atopic status of asthmatic patients and control subjects was ascertained by positive assays of IgE specific to house dust mites (HDMs [Dermatophagoides pteronyssinus]; allergen protein from HDMs, Der p1), cat, dog, mixed cockroaches, and mixed molds by fluorescence enzyme immunoassay (AutoCAP analyzer; Pharmacia Diagnostics AB; Uppsala, Sweden).22 Sensitization to local pollens was not tested due to its low prevalence in our community.23 The grading of a specific IgE into radioallergosorbent test classes 1 to 6 was performed according to the manufacturer’s grading recommendations, with specific IgE concentrations >= 0.35 kU/L being positive. Subjects were defined as atopic if they had at least one positive result on testing for allergen-specific IgE. Eosinophil cationic protein (ECP) was similarly measured (AutoCAP analyzer; Pharmacia Diagnostics AB). Plasma concentrations of sFas were determined by the human Fas (CD95) quantikine enzyme-linked immunosorbent assay kit (R&D Systems Inc; Minneapolis, MN) using recombinant sFas as the standard.

Cell Preparation
Peripheral blood mononuclear cells (PBMCs) were prepared by centrifuging heparinized venous blood using a density gradient (Ficoll-Paque; Amersham Pharmacia Biotech Ltd; Uppsala, Sweden). The viability of the PBMCs was > 95%, as determined by the trypan blue exclusion method. PBMCs (1 x 106 cells/mL) either were freshly isolated for investigating the expression of the Bcl-2 protein or were cultured on 24-well culture plates in medium (RPMI 1640; Gibco Laboratories; Grand Island, NY) supplemented with 10% fetal calf serum (Gibco), 20 mM HCO(3-)-free N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (Gibco) at 37°C, and 5% CO2 without or with DEX (0.1 and 1.0 µM) [CALBIOCHEM; La Jolla, CA]. After 24 h, the cells were harvested for flow cytometric analysis of apoptosis and the expression of the Bcl-2 protein.

Immunofluorescence Staining and Flow Cytometric Analysis
For analyzing the expression of intracellular Bcl-2 molecule, PBMCs were fixed, permeabilized, and stained with 50 µg/mL phycoerythrin-conjugated anti-Bcl-2 monoclonal antibody (mAb) [BD Biosciences Pharmingen; San Diego, CA] or 50 µg/mL isotypic control phycoerythrin-conjugated mouse IgG1 (BD Biosciences Pharmingen) for 30 min in ice. Thence, peridinin chlorophyll protein-conjugated CD3-specific mAb (BD Biosciences Pharmingen) was added for another 20 min. A two-color immunofluorescence analysis for Bcl-2 expression of the stained cells was performed using a flow cytometer (FACSCalibur flow cytometer; BD Biosciences Immunocytometry Systems; San Jose, CA) using appropriate software (CellQuest software; BD Biosciences Immunocytometry Systems). A forward-scatter/side scatter gate together with a CD3+ logical gate was set for T lymphocytes. A total of 5,000 events were collected in the log mode and were expressed as mean fluorescence intensity (MFI).

Assessment of Apoptosis
Briefly, PBMCs (105 to 106 cells) from 24-h cultures were washed and stained with peridinin chlorophyll protein-conjugated CD3-specifc mAb (BD Biosciences Pharmingen). The apoptosis of PBMC cultures was assessed using a staining kit (TACS annexin V-fluorescein isothiocyanate/propidium iodide staining kit; Trevigen Inc; Gaithersburg, MD).24 Three-color immunofluorescence analysis was performed (FACSCalibur flow cytometer) using appropriate software (CellQuest software). A total of 5,000 events were gated on forward scatter vs side scatter with a CD3+ logical gate set for T lymphocytes.

Statistical Analysis
Since the expressions of allergen-specific IgE, ECP, sFas, and Bcl-2, and the percentage of apoptotic cells were not in a Gaussian distribution, the Mann-Whitney rank sum test was used to assess the differences between the asthmatic patients and the control subjects. The Fisher exact test was used for the comparison of the allergen sensitization (atopy) between the asthmatic patients and control subjects. All analyses were performed using statistical software (SPSS for Windows, version 9.0; SPSS Inc; Chicago, IL). A p value of < 0.05 was considered to be significantly different. Unless otherwise specified, results are expressed as the median (interquartile range [IQR]).


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
Patients With Allergic Asthma and Control Subjects
The age, sex, lung functions, drug treatment, and atopic status of the study populations are summarized in Table 1 . The mean (± SD) FEV1 of the asthmatic patients was 2.2 ± 0.7 L/min (78.3 ± 17.1% of predicted normal values), while the FEV1/FVC ratio was 76.8 ± 11.2%. The severity of asthma in this group of patients according to the Global Initiative for Asthma guideline, which was based on daytime symptoms, nocturnal symptoms, and lung function, was as follows: intermittent asthma, 9 patients (23%); mild persistent asthma, 11 patients (27%); moderate persistent asthma, 17 patients (40%); and severe persistent asthma 4 patients (10%). Atopy to five common inhalants was found in all 41 patients (100%) and 12 of 30 control subjects (40%). The major environmental allergen was HDMs (Der p1) with 100% sensitization in patients vs 40% in control subjects (p < 0.0001), resulting in plasma concentrations of specific IgE to Der p1 being significantly elevated in patients (median, 45.6 kU/L [IQR, 16.8 to 71.7 kU/L] vs 0.2 kU/L [IQR, 0.1 to 0.6 kU/L], respectively; p < 0.0001). The plasma ECP concentration was also significantly higher in asthmatic patients (median, 4.2 µg/L [IQR, 2.2 to 8.6 µg/L] vs 1.8 µg/L [IQR, 1.2 to 2.3 µg/L], respectively; p < 0.0001).


View this table:
[in this window]
[in a new window]

  		Table 1.. Characteristics of the Study Populations*

 
DEX-Induced Apoptosis of T Lymphocytes
The percentages of apoptotic T cells from asthmatic patients and healthy control subjects were elevated by DEX (0.1 and 1 µM) in a dose-dependent manner (Fig 1 ). The percentages of apoptosis (mean ± SD) of DEX-treated T cells were found to be significantly higher than those of untreated T cells in each group (allergic asthmatic patients: medium only, 16.5 ± 4.8%; 0.1 µM DEX, 24.1 ± 6.5%; 1 µM DEX, 29.0 ± 6.5%; healthy control subjects: medium only, 13.6 ± 3.1%; 0.1 µM DEX, 19.0 ± 3.7%; 1.0 µM DEX, 25.8 ± 5.57%).



View larger version (15K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1.. The dose-dependent, DEX-induced apoptosis of PBMCs (gated for T lymphocytes) from asthmatic patients and control subjects is shown. After PBMCs were cultured without DEX (0 µM DEX) or with DEX at 0.1 and 1 µM for 24 h, the percentage of apoptosis was analyzed by flow cytometry. Each point represents the mean percentage of apoptotic cells from each group ({blacktriangleup}, allergic asthmatic patients; {blacktriangledown}, healthy control subjects), and the error bar represents the SD. Statistical differences between DEX-treated and medium-treated cells were determined by the Mann-Whitney rank sum test. * = p < 0.001 for healthy control subjects; ** = p < 0.001; *** = p = 0.038 (compared with 0.1 µM DEX) for asthmatic patients.

 
As shown in Figure 2 , the percentage increase (with respect to the basal apoptosis of PBMCs cultured with medium) of apoptotic T cells from allergic asthmatic patients was significantly higher when compared with the control subjects in terms of treatment with 0.1 µM DEX (median, 10.9% [IQR, 3.5 to 15.0%] vs 5.1% [IQR, 2.1 to 6.0%], respectively; p = 0.016). Although there was no significant difference between the percentage increase in the T-cell apoptosis of allergic asthmatic patients and control subjects receiving treatment with 1 µM DEX (p > 0.05), our results suggested that the T lymphocytes of asthmatic patients were more susceptible to low-dose DEX-induced apoptosis than those of healthy control subjects.



View larger version (13K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2.. The effect of DEX on the apoptosis of PBMCs (gated for T lymphocytes) from allergic asthmatic patients and control subjects that were cultured in medium alone or 0.1 µM DEX for 24 h is shown. The results are expressed as the percentage increase (with respect to the basal apoptosis of PBMCs cultured with medium) of apoptotic T cells on treatment with 0.1 µM DEX. The median is indicated by the horizontal bar, and each triangle represents an individual. The statistical differences were determined by the Mann-Whitney rank sum test. * = p = 0.016.

 
Plasma Concentrations of sFas
The plasma concentration of sFas in asthmatic patients was significantly higher than that of the healthy control subjects (median, 3.1 ng/mL [IQR, 2.5 to 3.9 ng/mL] vs 2.6 ng/mL [IQR, 2.2 to 2.9 ng/mL], respectively; p = 0.033) [Fig 3 ].



View larger version (15K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 3.. The plasma concentrations of sFas in patients with allergic asthma are shown. The median is indicated by the horizontal bar, and each triangle represents an individual. The difference between asthmatic patients and control subjects was determined by the Mann-Whitney rank sum test. * = p = 0.033.

 
Expression of Bcl-2 Protein
As shown in the representative histogram of Figure 4 , top left, a, the ex vivo expression of Bcl-2 in the T cells of a patient with allergic asthma was lower than that of a control subject (Fig 4 , top right, b). The expression of Bcl-2 in T cells from this patient and others with allergic asthma was significantly lowered when compared with the control subjects (MFI, 21.3 [IQR, 14.1 to 30.2] vs 36.3 [IQR, 24.2 to 51.6]; p < 0.001) [Fig 5 , top, a]. The in vitro Bcl-2 expressions of T cells cultured with or without DEX for asthmatic patients (Fig 4 , top middle left, c, bottom middle left, e, and bottom left, g) were lower than those of control subjects (Fig 4 , top middle right, d, bottom middle right, f, and bottom right, h). The expression of Bcl-2 protein on T cells from both asthmatic patients and control subjects was not significantly altered while receiving treatment in vitro with DEX (0.1 and 1.0 µM; all p > 0.05), while the in vitro expression of Bcl-2 was significantly lower in asthmatic patients compared to healthy control subjects (medium only, 35.0 [IQR, 28.2 to 41.8] vs 38.0 [IQR, 32.7 to 43.5], respectively; 0.1 µM DEX, 32.5 [29.6 to 39.9] vs 40.0 [33.3 to 43.6], respectively; 1.0 µM DEX, 34.4 [29.8 to 39.6] vs 36.4 [33.9 to 43.8], respectively; all p < 0.05) [Fig 5 , bottom, b].



View larger version (35K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 4.. The expression of the Bcl-2 protein in PBMCs (gated for T lymphocytes) was illustrated by representative histograms (shaded portion) of an asthmatic patient (left panels) and a healthy control subject (right panels). The Bcl-2 expressions of freshly isolated PBMCs ex vivo are shown in top left, a, and top right, b. The Bcl-2 expressions of PBMCs that were cultured with or without DEX for 24 h are shown for medium cultures (top left middle, c, and top right middle, d), for 0.1 µM DEX treatment (bottom left middle, e, and bottom right middle, f), and for 1 µM DEX treatment (bottom left, g, and bottom right, h). The expression, as shown by the percentage of Bcl-2-positive cells within M2, was evaluated by comparison with a negative control subject containing an isotypic mouse IgG1 antibody (gray line portion). M1-marker index 1; M2-marker index 2.

 


View larger version (18K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 5.. The expression of Bcl-2 molecule in (top, a) fresh and (bottom, b) cultured (with or without DEX treatment for 24 h) T lymphocytes from allergic asthmatic patients (n = 25) and healthy control subjects (n = 20). The results are expressed as the MFI of Bcl-2 expression. The median is indicated by the horizontal bar, and each triangle represents an individual. The difference between asthmatic patients and control subjects was determined by the Mann-Whitney rank sum test. * = p < 0.001; ** = p < 0.05.

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
In recent years, it has become evident that T lymphocytes orchestrate allergic inflammation by secreting T helper (Th)-2 cytokines to trigger the local recruitment and accumulation of other inflammatory cells such as neutrophils, eosinophils, and mast cells.4 However, it is still not clear how such an inductive phase cannot be down-regulated in allergic asthmatic patients. One of the mechanisms for controlling the overreactivity of T-cell-mediated responses is apoptosis. Some studies4 7 have suggested that defective apoptosis of T cells, especially CD4+ Th cells, may account for the prolonged survival of activated T cells in allergic asthmatic patients.

On the addition of DEX in vitro, the peripheral blood T cells of allergic asthmatic patients and control subjects underwent dose-dependent elevations in apoptosis (Fig 1) . The apoptotic susceptibility of T cells in asthmatic patients to treatment with 0.1 µM DEX was higher when compared with healthy control subjects (Fig 2) . Brunetti et al25 have demonstrated that the sensitivity to DEX-induced apoptosis is acquired soon after T-cell activation. Evidence has indicated also that activated T cells are more susceptible than resting cells to apoptosis induction.26 27 28 Based on these findings, our data suggest that the asthmatic T lymphocytes might be preactivated in vivo and, hence, acquire increased susceptibility to apoptosis induction by DEX in vitro. Thus, we conclude that the higher apoptotic susceptibility of T lymphocytes in asthmatic patients after they receive DEX treatment in vitro might be important for the therapeutic actions of corticosteroids in patients with allergic asthma.

Since sFas was previously shown to competitively inhibit the binding of membrane Fas antigen to Fas-ligand on the cell surface and, hence, to inhibit the Fas-mediated apoptotic pathway,6 29 the elevated plasma concentrations of sFas in asthmatic patients (Fig 3) might explain the down-regulated apoptosis of asthmatic T cells.

In order to delineate the mechanisms involved in the prolonged survival of immune cells in asthmatic patients, some studies have focused on the role of an apoptosis inhibitor (ie, Bcl-2) in the process of allergic inflammation.2 30 31 However, the detailed regulatory mechanisms of the Bcl-2 family on the apoptosis of peripheral T lymphocytes in asthmatic patients are not well-understood. Our present results demonstrate that the ex vivo expression of the Bcl-2 molecule in the T cells of asthmatic patients was significantly lower than that in healthy control subjects (Fig 4 , 5 , top, a). However, a previous study32 has indicated the elevation of Bcl-2 expression in induced sputum mononuclear cells from non-steroid-treated asthmatic patients. Another recent study has illustrated the down-regulated expression of prosurvival genes (eg, Bcl-2A1) of the Bcl-2 family in asthmatic patients, giving rise to a net proapoptotic profile of Bcl-2 family genes.33 In addition, Bcl-2 expression in CD4+ cells has been found to be reduced in the bronchi of asthmatic patients.34 The difference between our results and those of others may be explained by the differential influence of the inflammatory environment (ie, peripheral blood vs airway) and cytokines on lymphocyte subsets (Th1 cells vs Th2 cells), since a Th1/Th2 imbalance may result from the preferential apoptosis of the Th1 subset, perhaps relating to the reduced Bcl-2 expression. However, the in vitro treatment of PBMCs with DEX had no significant effect on the Bcl-2 expression of T cells from both allergic asthmatic patients and control subject subjects (Fig 4 , top left middle, c, to bottom right, h, Fig 5 , bottom, b), suggesting that DEX did not exert any direct effect on the Bcl-2 protein in vitro. In conclusion, a higher apoptotic susceptibility during DEX treatment in vitro as well as lower ex vivo and in vitro expressions of the Bcl-2 molecule of T lymphocytes in asthmatic patients were found when compared with healthy control subjects. Further investigations on the dysregulation of activation-induced cell death of T lymphocytes and the effect of DEX on activation-induced cell death are required.


   Footnotes
 
Abbreviations: Bcl = B-cell lymphoma; DEX = dexamethasone; ECP = eosinophil cationic protein; GC = glucocorticoid; IQR = interquartile range; mAb = monoclonal antibody; MFI = mean fluorescence intensity; PBMC = peripheral blood mononuclear cell; sFas = soluble Fas; Th = T helper

This study was supported by a donation from Zindart (De Zhen) Foundation Ltd, Hong Kong.

Received for publication November 7, 2001. Accepted for publication April 26, 2002.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Yssel, H, Groux, H (2000) Characterization of T cell subpopulations involved in the pathogenesis of asthma and allergic diseases. Int Arch Allergy Immunol 121,10-18[CrossRef][ISI][Medline]
  2. Ohta, K, Yamashita, N Apoptosis of eosinophils and lymphocytes in allergic inflammation. J Allergy Clin Immunol 1999;104,14-21[CrossRef][ISI][Medline]
  3. Robinson, DS, Hamid, Q, Ying, S, et al Predominant TH2-like bronchoalveolar T-lymphocyte population in atopic asthma. N Engl J Med 1992;326,298-304[Abstract]
  4. Romagnani, S The role of lymphocytes in allergic disease. J Allergy Clin Immunol 2000;105,399-408[CrossRef][ISI][Medline]
  5. Walker, C, Bode, E, Boer, L, et al Allergic and nonallergic asthmatics have distinct patterns of T-cell activation and cytokine production in peripheral blood and bronchoalveolar lavage. Am Rev Respir Dis 1992;146,109-115[ISI][Medline]
  6. Nagata, S, Golstein, P The Fas death factor. Science 1995;267,1449-1456[Abstract/Free Full Text]
  7. Jayaraman, S, Castro, M, O’Sullivan, M, et al Resistance to Fas-mediated T cell apoptosis in asthma. J Immunol 1999;162,1717-1722[Abstract/Free Full Text]
  8. Barnes, PJ Therapeutic strategies for allergic diseases. Nature 1999;402(suppl),B1-B40
  9. Oneda, K Dexamethasone-induced apoptosis in peripheral T lymphocytes from patients with asthma. Arerugi 1999;48,13-22[Medline]
  10. Wen, LP, Madani, K, Fahrni, JA, et al Dexamethasone inhibits lung epithelial cell apoptosis induced by IFN-{gamma} and Fas. Am J Physiol 1997;273,L921-L929[Abstract/Free Full Text]
  11. Ohsako, S, Hara, M, Harigai, M, et al Expression and function of Fas antigen and bcl-2 in human systemic lupus erythematosus lymphocytes. Clin Immunol Immunopathol 1994;73,109-114[CrossRef][ISI][Medline]
  12. Itoh, N, Yonehara, S, Ishii, A, et al The polypeptide encoded by the cDNA for human cell surface antigen Fas can mediate apoptosis. Cell 1991;66,233-243[CrossRef][ISI][Medline]
  13. Kato, M, Nozaki, Y, Yoshimoto, T, et al Different serum soluble Fas levels in patients with allergic rhinitis and bronchial asthma. Allergy 1999;54,1299-1302[CrossRef][ISI][Medline]
  14. Rose, LM, Latchman, DS, Isenberg, DA Apoptosis in peripheral lymphocytes in systemic lupus erythematosus: a review. Br J Rheumatol 1997;36,158-163[Abstract/Free Full Text]
  15. Vignola, AM, Chanez, P, Chiappara, G, et al Evaluation of apoptosis of eosinophils, macrophages, and T lymphocytes in mucosal biopsy specimens of patients with asthma and chronic bronchitis. J Allergy Clin Immunol 1999;103,563-573[CrossRef][ISI][Medline]
  16. Druilhe, A, Wallaert, B, Tsicopoulos, A, et al Apoptosis, proliferation, and expression of Bcl-2, Fas, and Fas ligand in bronchial biopsies from asthmatics. Am J Respir Cell Mol Biol 1998;19,747-757[Abstract/Free Full Text]
  17. American Thoracic Society. Guidelines for the evaluation of impairment/disability in patients with asthma. Am Rev Respir Dis 1993;147,1056-1061[ISI][Medline]
  18. American Thoracic Society. Standardization of spirometry, 1994 update. Am J Respir Crit Care Med 1995;152,1107-1136[ISI][Medline]
  19. Lam, KK, Pang, SC, Allan, WG, et al Predictive nomograms for forced expiratory volume, forced vital capacity, and peak expiratory flow rate, in Chinese adults and children. Br J Dis Chest 1983;77,390-396[ISI][Medline]
  20. National Asthma Education and Prevention Program. Expert panel report 2: guidelines for the management of asthma. April 1997 National Institutes of Health Bethesda, MD. Publication No. 97–4051
  21. National Heart, Blood, and Lung Institute. Global strategy for asthma management and prevention: WHO/NHLBI workshop report. 1995 National Heart, Lung, and Blood Institute Bethesda, MD. Publication No. 95–3659
  22. Lam, CWK, Fung, HK, Vrijmoed, LLP, et al Aetiology of allergic rhinitis in Hong Kong. Allergol Int 1998;47,23-28[CrossRef]
  23. Leung, R, Ho, P, Lam, CWK, et al Sensitization to inhalant allergens as a risk factor for asthma and allergic diseases in Chinese. J Allergy Clin Immunol 1997;99,594-599[CrossRef][ISI][Medline]
  24. Ho, CY, Wong, CK, Li, EK, et al Effects of dexamethasone on the expression of Fas molecule and apoptosis of lymphocytes in patients with systemic lupus erythematosus. Immunol Invest 2001;30,231-243[CrossRef][ISI][Medline]
  25. Brunetti, M, Martelli, N, Colasante, A, et al Spontaneous and glucocorticoid-induced apoptosis in human mature T lymphocytes. Blood 1995;86,4199-4205[Abstract/Free Full Text]
  26. Tuosto, L, Cundari, E, Montani, MSG, et al Analysis of susceptibility of mature human T lymphocytes to dexamethasone-induced apoptosis. Eur J Immunol 1994;24,1061-1065[ISI][Medline]
  27. Owen-Schaub, LB, Yonehara, S, Crump, WL, et al DNA fragmentation and cell death is selectively triggered in activated human lymphocytes by Fas antigen engagement. Cell Immunol 1992;140,197-205[CrossRef][ISI][Medline]
  28. Nishioka, Y, Lipsky, PE The role of CD40-CD40 ligand interaction in human T cell-B cell collaboration. J Immunol 1994;153,1027-1036[Abstract]
  29. Cheng, J, Zhou, T, Liu, C, et al Protection from Fas-mediated. apoptosis by a soluble form of the Fas molecule. Science 1994;263,1759-1762[Abstract/Free Full Text]
  30. Chung, IY, Nam-Kung, EK, Lee, NM, et al The downregulation of bcl-2 expression is necessary for theophylline-induced apoptosis of eosinophils. Cell Immunol 2000;203,95-102[CrossRef][ISI][Medline]
  31. Jang, AS, Choi, IS, Lee, S, et al Bcl-2 expression in sputum eosinophils in patients with acute asthma. Thorax 2000;55,370-374[Abstract/Free Full Text]
  32. Hamzaoui, A, Hamzaoui, K, Salah, H, et al Lymphocytes apoptosis in patients with acute exacerbation of asthma. Mediators Inflamm 1999;8,237-243[CrossRef][ISI][Medline]
  33. Brutsche, MH, Brutsche, IC, Wood, P, et al Apoptosis signals in atopy and asthma measured with cDNA arrays. Clin Exp Immunol 2001;123,181-187[CrossRef][ISI][Medline]
  34. Cormican, L, O’Sullivan, S, Burke, CM, et al IFN-{gamma} but not IL-4 T cells of the asthmatic bronchial wall show increased incidence of apoptosis. Clin Exp Allergy 2001;31,731-739[CrossRef][ISI][Medline]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Article Archive
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (6)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ho, C.-Y.
Right arrow Articles by Lam, C. W.-K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ho, C.-Y.
Right arrow Articles by Lam, C. W.-K.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS