Neurotophins are increased in bronchoalveolar lavage fluid after segmentalallergen provocation

The mechanisms linking inflammation and airway hyperresponsiveness in aller gic bronchial asthma are still not completely defined. Since neurotrophic f actors increase nerve excitability and neurotransmitter synthesis and are p roduced by immunocompetent cells, they are likely candidates as mediators o f inflammation and hyperresponsiveness. We tested the hypothesis that neuro trophin concentrations will increase in the bronchoalveolar lavage (BAL) fl uid from patients with asthma after segmental allergen provocation. For thi s purpose an individually standardized dose of allergen or saline was insti lled into different segments during bronchoscopy in eight: subjects with mi ld allergic bronchial asthma. Segments were then lavaged 10 min and 18 h af ter allergen challenge or saline instillation. There was a significant incr ease in the neurotrophins nerve growth factor, brain-derived neurotrophic f actor, and neurotrophin-3 in BAL fluids 18 h after allergen but not saline challenge. We conclude that neurotrophins are produced endobronchially foll owing allergen provocation, suggesting a contribution to the pathogenesis o f asthma.