BILATERAL INCREASES IN HISTAMINE AFTER UNILATERAL NASAL ALLERGEN CHALLENGE

Studying the inflammatory response that follows the early response to nasal challenge with antigen provides a better understanding of allerg ic rhinitis than just studying the immediate (early) response. Nine al lergic volunteers were challenged unilaterally with antigen-containing discs, and bilateral changes in physiologic responses as well as in t hat concentration of histamine in nasal secretions were measured for 1 1 h. We found significant immediate increases in symptoms, sneezes, ip silateral nasal airway resistance, and ipsilateral histamine in the ea rly phase response. Two-thirds of the allergen-challenged volunteers s howed increases in physiologic parameters or histamine in the hours af ter allergen challenge. The pooled data of all subjects exhibited sign ificant increases in bilateral nasal airway resistance and in ipsilate ral and contralateral histamine, hours after unilateral provocation. T hese responses differed significantly from control subjects. In anothe r group of 11 volunteers challenged ipsilaterally with antigen, the nu mber of basophils increased both on the side of challenge and on the c ontralateral side. The magnitude of the increase on the ipsilateral si de correlated with was increase on the contralateral side (r(s) = 0.72 ). The basophils are the most likely source of the contralateral incre ase in histamine as they are on the ipsilateral side. Although the mec hanisms underlying this contralateral increase in basophils and histam ine are not known, we speculate that delayed, neurogenic responses pla y a contributory role.