Effect of H1 Receptor Blockade on the Early and Late Response to Cutaneous Allergen 2

We investigated whether cutaneous antigen-induced inflamma-tory cell infiltration and mediator release were modified by H1 receptor antagonists. Three chemically unrelated antihistamines (cetirizine, promethazine and chlorpheniramine) were tested in three groups of allergic subjects in a double-blind, crossover design. Chamber fluids were collected for 1 2 hr and histamine release, prostaglandin D2 production and cellular infiltration were quantified. Cetirizine significantly decreased late leukocyte mi-gration into antigen-challenged chambers: eosinophils by 68% (P <.04), basophils by 64 % (P <.04) and neutrophils by 72% (P <.04), whereas mononuclear cells were not significantly affected. No alteration in the numbers of peripheral blood leu-kocytes or eosinophils occurred while on cetirizine treatment, suggesting that the decrease in inflammatory cells during th