THE EFFECT OF CETIRIZINE ON SULFIDOLEUKOTRIENE PRODUCTION BY BLOOD LEUKOCYTES IN CHILDREN WITH ALLERGIC RHINITIS

Twelve children with allergic rhinitis due to monosensitivity to Derma tophagoides pteronyssinus (Dp) took part in a placebo-controlled, doub le-blind, crossover study to evaluate the effect of cetirizine, a seco nd-generation, nonsedating H-1-blocker-type antihistamine, on sulfidol eukotriene releasability by blood leukocytes and to determine its corr elation with clinical findings and nasal challenge scores. Sultidoleuk otriene release by blood leukocytes was determined by the cellular all ergen stimulation test (CAST), which measures leukotriene (LT)C-4, LTD (4), and LTE(4), all in one assay. Compared to placebo, cetirizine sig nificantly (P<0.05) decreased daily symptom scores of nasal discharge, nasal itching, and sneezing, as well as the number of sneezings after nasal challenge with the antigen, without alleviating nasal obstructi on (P>0.05). It also suppressed both early (P<0.05) and late skin reac tions to intradermal tests. Although cetirizine did not influence in v itro sulfidoleukotriene production by blood leukocytes with buffer or anti-IgE (P>0.05), it substantially reduced the release of these media tors upon challenge with Dp antigen. Furthermore, there was a high cor relation between the number of sneezes after challenge and the amount of sulfidoleukotriene released in nine patients (r = 0.78; P<0.01). It is concluded that the amount of sulfidoleukotrienes produced by blood leukocytes in vitro may reflect the nasal hyperreactivity of the pati ent, and that cetirizine, which is highly effective in the treatment o f allergic rhinitis, owes part of its effect to inhibition of sulfidol eukotriene releasability by blood leukocytes in children.