TREATMENT WITH HOT, HUMID AIR REDUCES THE NASAL RESPONSE TO ALLERGEN CHALLENGE

Ten subjects with asymptomatic seasonal allergy, outside of their alle rgy season, underwent allergen provocation following 1 hour of exposur e to air at either 20 degrees C and 30% relative humidity (RH) or air at 37 degrees C and 90% RH. The ipsilateral al changes following antig en challenge were compared under the two conditions. Conditioning of t he nose to 37 degrees C, 90% RH reduced total histamine release (7.9 /- 1.8 ng vs 4.2 +/- 1.3 ng; p less than or equal to 0.05), sneezes (6 +/- 2 vs 3 +/- 1; p less than or equal to 0.05), pruritus (score of 1 7.4 +/- 6.0 vs score of 2.0 +/- 1.8 out of a total score of 100, p les s than or equal to 0.01), nasal airway resistance (1.4 +/- 0.8 kPa/L/s ec vs 0.2 +/- 0.1 kPa/L/sec; p less than or equal to 0.05), human seru m albumin levels (389.6 +/- 53.4 mu g vs 242.2 +/- 37.9 mu g; p less t han or equal to 0.05), and congestion (score of 23.8 +/- 4.8 vs score of 10.6 +/- 5.4 out of a total score of too, p less than or equal to 0 .01). It had ilo effect on the volume of secretions (p = 0.8), lactofe rrin levels (p = 0.3), or rhinorrhea (p = 1.0). Thus air at 37 degrees C and 90% RH partially reduces the early response to antigen. its eff ects are greatest on histamine release, the vascular response, and neu ral responses, with no effect on the glandular response. The mechanism s underlying these effects are unknown.