Allergen provocation increases TH2-cytokines and FOXP3 expression in the asthmatic lung.
BACKGROUND
Allergic asthma is caused by allergen-specific IgE and T-helper cell (Th) type 2 responses towards airborne allergens. The objective of this study was to investigate local and systemic regulatory mechanisms in the early asthmatic response to bronchial allergen provocation.


METHODS
Birch pollen-allergic patients with mild asthma (n = 13) and healthy nonallergic controls (n = 14) were subjected to bronchoalveolar lavage (BAL) and blood sampling. On patients BAL was performed twice: without preceding provocation ('before samples') and 24 h after bronchial provocation with birch pollen allergen. Lymphocytes in BAL and peripheral blood mononuclear cells (PBMCs) were phenotyped by multi-colour flow cytometry and cytokines measured by cytometric bead array. Proliferation and secreted cytokines were analysed in allergen-stimulated PBMCs, CD25(+) depleted PBMCs and PBMCs with IL-10 neutralizing antibodies.


RESULTS
The numbers of CD69(+) and FOXP3(+) lymphocytes were higher in BAL after compared with before allergen provocation in asthmatic patients. Moreover, allergen provocation increased expression of FOXP3 in CD4(+)CD25(bright) cells. The cytokine profile in BAL fluid from asthmatics revealed higher levels of IL-5, compared with the controls, and an increase in IL-5, IL-6, IL-9 and IL-10 after allergen provocation. Pollen allergen stimulated PBMC cultures from asthmatic patients produced elevated levels of IL-5 and IL-13 compared with the controls, which were not affected by depletion of CD25(+) cells or IL-10 neutralization.


CONCLUSIONS
Despite an increase in CD4(+)CD25(bright) cells expressing high levels of FOXP3 in response to bronchial allergen provocation, asthmatic patients exhibit enhanced levels of Th2 cytokines in the lung, which may indicate an inability among infiltrating cells to suppress Th2 responses.
Clinical Immunology and Allergy Unit, Department of Medicine, Karolinska Institute, University Hospital, Stockholm, Sweden.
S
S
Thunberg
G
G
Gafvelin
M
M
Nord
R
R
Grönneberg
J
J
Grunewald
A
A
Eklund
M
M
van Hage
D000328:Adult; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000276:immunology*; D029662:Betula / Q000276:immunology; D001985:Bronchial Provocation Tests; D018893:Bronchoalveolar Lavage; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D002469:Cell Separation; D016207:Cytokines / Q000096:biosynthesis / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000276:immunology*; D006801:Humans; D008168:Lung / Q000276:immunology* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology*; D055815:Young Adult
D000485:Allergens; D016207:Cytokines; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors