Allergens induce apoptosis in lymphocytes from atopic patients

Repeated stimulation of immune cells may induce an "activation-induced cell death" (AICD) program. Allergy is characterized by the cyclic activation o f allergen-reactive immune cells. To study the effects of allergen stimulat ion in cell proliferation and apoptosis in atopic subjects, peripheral bloo d mononuclear cells (PBL) from 40 atopic patients with positive reactivity to the allergens Olea Europaea (OE) and Lollium Perenne (LP) (20 without im munotherapy and 20 with specific immunotherapy) and 10 normal subjects were cultured with the allergens OE and LP. PBL from atopic patients proliferat e more vigorously than cells from normal subjects alter culture in vitro wi th both allergens, although PBL from atopic subjects without immunotherapy proliferate more than PBL from atopic subjects with immunotherapy. The stud y of cell proliferation shows that in atopic patients PBL mainly exhibit th e CD4/CD45RO phenotype. This preferential proliferation is more evident in PBL from atopic patients created without immunotherapy. Cell culture with specific allergens induces apoptosis in PBL from atopic p atients. The percentage of apoptosis increased when atopic patients had bee n previously treated with immunotherapy. In addition to the observed increa se in cell proliferation, apoptosis mainly occurs in the CD45RO cells chat support the involvement of these cells in allergy. Furthermore, results obt ained in cells from immunized patients suggest that an AICD process may par tly at least explain the mechanism of action of allergen immunotherapy. (C) American Society for Histocompatibility and Immunogenetics, 1999. Publishe d by Elsevier Science Inc.