Release of Histamine, Prostaglandins, and Leukotrienes after Antigen Challenge in Hayfever Subjects

Nasal washes before and at intervals after nasal challenge with mixed grass pollen extract were carried out in nine patients with allergic rhinitis and four control subjects. In the nasal wash, histamine was measured using the radioenzymatic method, prostaglandins (PGs) and leukotrienes (LTs) were measured by high pressure liquid chromatography. Control subjects did not react to allergen challenge. Small amounts of histamine (0.47 ± 0.23 ng/ml) and PGD2 were found in the nasal fluid before challenge with no increase in either mediator after challenge. Leukotrienes were not found before or after challenge. Subjects with allergic rhinitis developed sneezing, rhinorrhea, and stuffy nose after challenge. High levels of histamine (5.3 ± 7.0 ng/ml) and PGD2 (2.7 ± 3.2 ng/ml) were found in the first prechallenge wash even though the subjects were asymptomatic. The second prechallenge wash showed reduction of histamine (2.8 ± 5.2 ng/ml) and PGD2 (1.4 ± 1.8 ng/ml). Five to 15 minutes after antigen challenge, there was a rise in histamine and PGD2 in four of nine subjects. No LTs were detectable in the prechallenge wash. Five of nine subjects showed a rise in LTC4 and/or LTE4, immediately after challenge. Our results showed that although nasal challenge with antigen can induce the release of mediators in seven of nine subjects with allergic rhinitis, the profile of mediator release was variable, and there was no correlation between the type or amount of mediator released and the severity of the nasal symptoms. The pathogenetic role of these mediators in pollenallergic rhinitis needs further evaluation.