DEPLETION OF CIRCULATING ALLERGEN-SPECIFIC T-H2 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 or iented toward a T-H2 phenotype, characterized bg production of IL-4, I L-5, IL-10, and IL-13, Egress of T cells from blood to airways after a llergen challenge has been described. Objective: We have studied a coh ort of six patients with asthma who had multiple allergies to investig ate how exposure to allergen afferts the proliferation of peripheral C D4(+) T lymphocytes with different allergen specificities and lymphoki ne profiles. Methods: For each patient, CD4(+) T cell lines were gener ated 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 r esponse to the same allergens was measured before and 24 hours after i nhalation challenge with a sensitizing allergen. Results: We found tha t each single sensitizing allergen can deplete peripheral blood of T-H 2-type CD4+ T lymphocytes specific for all sensitizing allergens, but not of T-H1-type CD4(+) T lymphocytes. Conclusions: Our results sugges t the existence of mechanisms capable of sorting disease-associated an tigen specificities together with defined lymphokine patterns into T l ymphocytes that can migrate to target organs, in allergic asthma.