Studies of bronchoalveolar lavage (BAL) fluid from patients with allergic asthma have demonstrated active migration of eosinophils into the bronchial lumen after allergen challenge. The mechanisms mediating this eosinophil infiltration and cell activation are largely unexplained. The expression of several cell-surface molecules was measured on eosinophils derived from blood and BAL fluid 4 h after an allergen-induced early asthmatic reaction in order to find indications for a role of these molecules during extravasation to and activation in the bronchial compartment. Nine patients with allergic asthma participated in the study. An eosinophil-specific, high-depolarization signal enabled us to measure expression on eosinophils in a fluorescence activated cell sorter (FACS) analysis without isolation of these cells. Eosinophils recovered from BAL showed a different phenotype than blood eosinophils; upregulation of CR-3, p150/95, CD67, and CD63, and downregulation of L-selectin indicate that the cells are activated in terms of degranulation. Up-regulation of intercellular adhesion molecule-1 (ICAM-1), LFA-3, and human leukocyte antigen II (HLA-II) might enable cell-cell contact between T-lymphocytes and eosinophils, probably leading to immunomodulation and cell activation. The finding that eosinophils in BAL are activated and can interact with T cells is further evidence for the proinflammatory role of these cells in allergic asthma.

Eosinophils play an important role in the pathogenesis of asthma. Several pro-inflammatory responses of eosinophils are primed in vivo in this disease. The aim of the present study was to investigate whether regular antiasthma treatment could modulate priming-sensitive cytotoxic mechanisms of human eosinophils.In a randomized, two-centre, double-blind parallel group study, the effect of 8 weeks of treatment with salmeterol xinafoate 50 mg b.i.d., beclomethasone dipropionate 400 mg b.i.d. or both on pulmonary function and the activation of primingsensitive cytotoxic mechanisms of eosinophils, i.e. degranulation of eosinophil cationic protein (ECP) in serum, and activation of isolated eosinophils in the context of induction of the respiratory burst and release of platelet-activating factor (PAF) were tested. These effects were evaluated in 40 allergic asthmatics before and 24 h after allergen inhalation challenge.Whereas baseline forced expiratory volume in one second (FEV1) improved in all treatment groups, only treatment with a combination of salmeterol and beclomethasone significantly inhibited the allergen-induced increase in serum ECP, and (primed/ unprimed) PAF-release, suggesting inhibition of eosinophil priming after allergen challenge. In contrast to the combination therapy, monotherapy with beclomethasone had no influence on allergen-induced PAF-release, suggesting an additional antiinflammatory effect of salmeterol during combination therapy. Monotherapy with beclomethasone inhibited the prechallenge serum-treated zymosan (STZ) (0.1 mg . mL -1 )-induced respiratory burst and the allergen-induced increase in serum ECP levels, reflecting pre-and postchallenge anti-inflammatory effects. During monotherapy with salmeterol, an allergen-induced increase in serum ECP concentration and STZ (0.1 mg . mL -1 )-induced respiratory burst was observed, suggesting that treatment with salmeterol alone had no effect on priming-sensitive eosinophil cytotoxic mechanisms.In conclusion, this study shows that standard asthma therapy leads to inhibition of eosinophil priming of cytotoxic mechanisms in vivo. Eur Respir J 1999; 14: 915±922.

We conclude that allergen inhalation challenge causes a flare up of the skin lesions in atopic dermatitis patients. This was more prominent in atopic dermatitis patients who already suffered from an IgE-mediated allergic inflammation in the lung.

It is unclear whether the presence and severity of atopic dermatitis (AD) is predictive for the occurrence and severity of early and late asthmatic responses to inhaled allergens. The aim of this study was to compare the bronchial effects of allergen inhalation challenge in allergic asthma (AA) and atopic dermatitis.We therefore studied these responses in: nine patients with mild-to-moderate AA without AD; eight patients with mild-to-moderate AA and mild AD; eight patients with severe AD and mild AA; and eight patients with severe AD without AA. Allergen challenge was performed by inhaling doubling doses until the dose provoking a 20% fall in forced expiratory volume in one second (PC20) was reached. The late asthmatic reaction (LAR) was defined as a fall of >20% in peak expiratory flow (PEF) between 3 and 8 h after the challenge.All but four of the patients with severe AD without AA developed an early asthmatic response (EAR). A LAR was seen in all patients with severe AD and mild AA, in four patients with mild AD and mild-to-moderate AA, and in three patients with mild-to-moderate AA without AD. The LAR was most pronounced in patients with a combination of mild AA and severe AD. This could be explained, in part, by a decreased skin sensitivity in these patients, which made the Cockcroft formula for prediction of PC20 allergen less accurate in such patients.We conclude that patients with severe atopic dermatitis and mild asthma are at risk for developing pronounced late asthmatic responses after allergen exposure. This suggests that eosinophils activated in atopic dermatitis also predispose to airway inflammation.

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