SELECTED ARTICLES FROM THE RECENT LITERATURE 2004

11/29/04

Perennial allergic rhinitis - pathogenesis and management

Summary
Background - Perennial allergy rhinitis (PAR) is a year round inflammatory nasal disorder generally due to allergic reactions to multiple aero-allergens.

Findings - Bush of the Univ of Wisconsin in Madison, WI reviewed the pathogenesis and management of PA R. He pointed out that IgE antibody binding to allergenic epitopes on pollens, danders, dust mites and fungi/molds can activate mast cells and basophils to which such antibodies have bound. This results in the secretion of inflammatory mediators, including histamine, leukotrienes and cytokines.

Allergen avoidance should always to be tried as an early step in PAR management but is often not feasible a sufficient. A variety of pharmacotherapeutic approach (H1 antihistamines, nasal corticosteroid sprays, cromolyn/nedocromil, leukotriene antagonists) are worth trying but they do not alter the underlying allergic reaction although they may relieve symptoms to varying degree.

A recent addition to the therapeutic approach to PAR has been omalizumab (Omal), a humanized anti-IgE antibody that binds to free IgE in the plasma but not to IgE bound to the surface of mast cells or basophils. Thus, Omal can: 1) block the binding of free IgE to receptors on mast cells and basophils; 2) decrease the expression of the high affinity receptor for IgE (Fc epsilon RI); 3) does not activate mast cells to release mediators because it does not bind to IgE already bound to mast cells/basophils.

Pilot trials shown impressive efficacy of Omal in PAR in which the serum IgE levels are in the appropriate range. However, the need for repeated injections and attendant sizable cost may limit its use.

Reference
Treat Respir Med. 2004; 3:45 -47

Editor's Comments
This well-written review points out a number of aspects of the treatment of PAR often not emphasized in those previous reviews which focus more on seasonal allergic rhinitis due to exposure to outdoor aeroallergens. It should be stressed that the low-sedating antihistamines in current use: 1) do not significantly improve the nasal congestion which is a common, very troublesome manifestation of PAR; 2) have little or no anti-cholinergic activity. Therefore, they have little non-specific drying effect on watery nasal drainage. Thus, the newer antihistamines are usually of no benefit in URI.

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