Depletion of circulating allergen-specific TH2 T lymphocytes after allergen exposure in asthma.
BACKGROUND
In allergic asthma, CD4+ T lymphocytes are a fundamental component of local chronic inflammation. Their cytokine profile is oriented toward a TH2 phenotype, characterized by production of IL-4, IL-5, IL-10, and IL-13. Egress of T cells from blood to airways after allergen challenge has been described.


OBJECTIVE
We have studied a cohort of six patients with asthma who had multiple allergies to investigate how exposure to allergen affects the proliferation of peripheral CD4+ T lymphocytes with different allergen specificities and lymphokine profiles.


METHODS
For each patient, CD4+ T-cell lines were generated by in vitro stimulation with sensitizing and with nonsensitizing allergens, and IL-4 and interferon-gamma production by these lines was assessed. Proliferation of peripheral blood CD4+ T lymphocytes in response to the same allergens was measured before and 24 hours after inhalation challenge with a sensitizing allergen.


RESULTS
We found that each single sensitizing allergen can deplete peripheral blood of TH2-type CD4+ T lymphocytes specific for all sensitizing allergens, but not of TH1-type CD4+ T lymphocytes.


CONCLUSIONS
Our results suggest the existence of mechanisms capable of sorting disease-associated antigen specificities together with defined lymphokine patterns into T lymphocytes that can migrate to target organs, in allergic asthma.
Crimi
E
E
Dipartimento di Scienze Motorie e Riabilitative, Facoltà di Medicina e Chirurgia, University of Genoa, Italy.
Gaffi
D
D
Frittoli
E
E
Borgonovo
B
B
Burastero
S E
SE
D000280:Administration, Inhalation; D000328:Adult; D000485:Allergens / Q000008:administration & dosage / Q000097:blood* / Q000276:immunology*; D000818:Animals; D001249:Asthma / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008297:Male; D008875:Middle Aged; D008925:Mites / Q000276:immunology; D006109:Poaceae / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism
D000485:Allergens; D016207:Cytokines; D000939:Epitopes