INFLAMMATORY CELLULAR INFLUX FOLLOWS CAPSAICIN NASAL CHALLENGE

Capsaicin is a specific activator of sensory nerve endings. In rodents , mucosal application of capsaicin causes cells to infiltrate the tiss ue. To examine whether inflammatory-cell influx follows sensory-nerve activation in human airways, we delivered capsaicin (200 mu M) nasal s pray into the nares of 20 subjects (10 with allergic rhinitis and 10 n ormal), and measured the total leukocyte content of nasal ravage fluid obtained from 10 min to 4 h after the capsaicin challenge. Vehicle sp ray (1% EtOH in 0.9% saline) served as a control. Capsaicin challenge caused significant increases from prechallenge leukocyte counts at 20 min (p < 0.03), 30 min (p < 0.01), and 4 h (p < 0.03) after challenge, but not at 1 h after challenge (p = 0.68). Vehicle challenge did not increase leukocyte counts. Differential counts (performed on the 13 of 20 subjects from whom adequate specimens for differential counts were obtained) showed that neutrophils, eosinophils, and mononuclear cells increased at 10 min, 30 min, and 4 h (all p < 0.04), but not at 1 h a fter capsaicin challenge. Comparing the rhinitic to the normal subject s, we found no significant differences in the cellular response to cap saicin. These data support a nonspecific inflammatory effect of sensor y nerve activation in the human nose. Consequently, this work provides evidence that neurogenic inflammation can be induced in the human air way in vivo.