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The relationship between the release of platelet activating factor (PAF), leukotriene C4/D4/EE (LTC4/D4/E4) and prostaglandin D2 (PGD2) from nasal mucosa in vivo was examined in 24 rhinitis patients allergic to the house dust mite (HDM). During a double blind placebo controlled cross-over study 200 μg fluticasone propionate aqueous nasal spray (FPANS) was administered twice daily for two weeks. In response to allergen provocation (100, 1 000, 10 000 Bu/ml) and during the 9.5 h after this challenge the nasal fluid was obtained by washing the nose with saline and the levels of PAF, LTC4/D4/E4 and PGD2, as indicators of mediator release, were measured at the following time-points: baseline (t = − 1/2), allergen provocation with 10 000 Bu/ml (t = 0), 3.5 and 7.5 h (late phase). After allergen provocation the levels of the mediators increased in the nasal fluids of placebo treated patients (x-fold increase to baseline: PAF, 15; LTC4/D4/E4, 12; PGD2, 1.5). In fluids of patients treated with FPANS these levels tended to decrease. At the time of provocation the levels of PAF, LTC4/D4/E4 and PGD2 showed a significant correlation. The results indicate that these mediators can be used as markers of allergic reactions against house dust mites and that fluticasone propionate aqueous nasal spray tended to reduce the release of mediators of inflammation correlated with beneficial effects on clinical symptoms in this type of allergic reactions.

The history of allergic disease goes back to 1819, when Bostock described his own ‘periodical affection of the eyes and chest’, which he called ‘summer catarrh’. Since they thought it was produced by the effluvium of new hay, this condition was also called hay fever. Later, in 1873, Blackley established that pollen played an important role in the causation of hay fever. Nowadays, the definition of allergy is ‘An untoward physiologic event mediated by a variety of different immunologic reactions’. In this review, the term allergy will be restricted to the IgE-dependent reactions. The most important clinical manifestations of IgE-dependent reactions are allergic conjunctivitis, allergic rhinitis, allergic asthma and atopic dermatitis. However, this review will be restricted to allergic rhinitis. The histopathological features of allergic inflammation involve an increase in blood flow and vascular permeability, leading to plasma exudation and the formation of oedema. In addition, a cascade of events occurs which involves a variety of inflammatory cells. These inflammatory cells migrate under the influence of chemotactic agents to the site of injury and induce the process of repair. Several types of inflammatory cells have been implicated in the pathogenesis of allergic rhinitis. After specific or nonspecific stimuli, inflammatory mediators are generated from cells normally found in the nose, such as mast cells, antigen-presenting cells and epithelial cells (primary effector cells) and from cells recruited into the nose, such as basophils, eosinophils, lymphocytes, platelets and neutrophils (secondary effector cells). This review describes the identification of each of the inflammatory cells and their mediators which play a role in the perennial allergic processes in the nose of rhinitis patients.

Lcocabastine is an extremely potent and highly selective H1-receptor antagonist which has been specifically developed as eye drops and nasal spray for the treatment of allergic rhinoconjunctivitis. Clinical experience to date suggests that this topical antihistamine is at least as effective as other current first-line therapeutic approaches for the treatment of this condition, including oral H1-receptor antagonists and sodium cromoglycate. Onset of action is rapid, with clinical effects apparent within minutes of instillation. Moreover, duration of action is sufficiently long to permit a convenient twice-daily dosing regimen. Topical levocabastine is well tolerated with an adverse-effect profile comparable with that of placebo and sodium cromoglycate. As might be expected from the route of drug administration, application site reactions are the most frequent adverse effect associated with levocabastine eye drops and nasal spray with an incidence comparable with that seen in placebotreated controls. The availability of effective and well-tolerated topical antihistamines, such as levocabastine, is an important advance which broadens the range of therapeutic approaches available for the clinical management of allergic rhinoconjunctivitis. Levocabastine appears to be an attractive alternative to oral antihistamines as a first-line therapeutic option for the treatment of this atopic condition.