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Persistent airway T-lymphocyte activation in chronic corticosteroid-treated symptomatic asthma
A E Redington1, J W Wilson, A F Walls
1University Medicine, Southampton General Hospital, England.
Summary
Persistent airway T-lymphocyte activation occurs in symptomatic asthma patients despite corticosteroid treatment. This activation may not involve increased inflammatory cell recruitment in the airways.
Area of Science:
- Immunology
- Pulmonology
- Allergy and Clinical Immunology
Background:
- A subset of asthma patients experience persistent symptoms despite high-dose corticosteroid therapy.
- Limited data exists on the immunopathology of such corticosteroid-dependent asthma.
Purpose of the Study:
- To compare airway inflammation in symptomatic, corticosteroid-dependent asthma patients versus well-controlled asthma patients.
- Investigate T-lymphocyte activation and inflammatory cell presence in the airways.
Main Methods:
- Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsy.
- Flow cytometry (FACS) for T-lymphocyte subsets and activation markers.
- Immunohistochemistry for inflammatory cell quantification and immunoassay for inflammatory mediators.
Main Results:
- Greater T-lymphocyte expression of CD25 and HLA-DR in BAL fluid of symptomatic asthmatics.
- No significant differences in mast cells, eosinophils, or T-lymphocytes in bronchial biopsies.
- Similar levels of albumin, histamine, tryptase, and eosinophil cationic protein in BAL fluid between groups.
Conclusions:
- Symptomatic asthma, even with chronic corticosteroid treatment, shows persistent airway T-lymphocyte activation.
- Airway inflammation in these patients is not necessarily linked to increased inflammatory cell presence.