Enhanced expression of fas ligand (CD95L) on T cells after segmental allergen provocation in asthma

J Allergy Clin Immunol. 1999 Apr;103(4):649-55. doi: 10.1016/s0091-6749(99)70238-1.


Background: Little is known about the termination of the T-cell driven inflammation found in patients with allergic asthma.

Objective: Because signals delivered through Fas/Fas ligand can lead to T-cell apoptosis, we investigated the expression of Fas and Fas ligand on peripheral blood- and bronchoalveolar lavage fluid (BALF)-derived T cells and the percentage of apoptotic BALF cells in asthma.

Methods: Nine atopic subjects with mild asthma and 9 control subjects underwent segmental sham and allergen challenge. Flow cytometry was used to determine the T-cell expression of Fas and Fas ligand, and the terminal dUTP nick end labeled technique was applied to detect apoptotic BALF cells.

Results: In asthmatic and control subjects almost all T cells in the BALF expressed Fas antigen without changes after saline or allergen challenge. A small percentage of T cells in BALF expressed the Fas ligand. In asthmatic subjects, but not in control subjects, there was a significant increase in Fas ligand after allergen challenge (CD3: 0.8% +/- 0.6% [baseline] vs 3.2% +/- 1.2% [allergen challenge]; CD4: 1.8% +/- 0.0% vs 4.3% +/- 1.8%; CD8: 2.8% +/- 2.4% vs 9.1% +/- 4.8%) but not after saline challenge, with a significant correlation to the percentage of BALF eosinophils. Apoptotic BALF cells were localized exclusively in macrophages at a very low frequency (0.03% to 0.15%) and without changes after saline or allergen challenge in both groups.

Conclusion: In asthma there is an upregulation of Fas ligand on T cells in BALF after allergen challenge. Because there is no evidence for increased apoptosis, this phenomenon may reflect antigen-induced T-cell activation rather than apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Allergens / immunology*
  • Apoptosis
  • Asthma / immunology*
  • Bronchial Provocation Tests
  • Bronchoalveolar Lavage Fluid / cytology
  • Cell Count
  • Fas Ligand Protein
  • Female
  • Flow Cytometry
  • Humans
  • In Situ Nick-End Labeling
  • Leukocytes, Mononuclear / immunology
  • Ligands
  • Male
  • Membrane Glycoproteins / analysis*
  • T-Lymphocytes / immunology*
  • fas Receptor / analysis*


  • Allergens
  • FASLG protein, human
  • Fas Ligand Protein
  • Ligands
  • Membrane Glycoproteins
  • fas Receptor