Hot, Humid Air Partially Decreases the Response to Nasal Challenge with Antigen

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Abstract
Allergic rhinitis affects individuals in multiple environmental settings. We hypothesized that the environmental conditions of temperature and humidity had no effect on the early response to nasal challenge with antigen. To test this hypothesis, we selected 16 subjects with allergic rhinitis and challenged them intranasally with either ragweed or grass antigen after they were acclimatized for 1 hour in an environmental chamber to the following conditions: 4°C and 30% relative humidity (RH) (cold and dry environment), 22°C and 50% RH (normal indoor environment), and 37°C and 90% RH (hot and humid environment). The subjects remained in the chamber and were challenged with three increasing doses of antigen. Their response was measured by counting the number of sneezes and measuring the levels of histamine, N-alpha-tosyl-L-arginine methyl ester (TAME)-esterase activity, albumin, and lacto ferrin in recovered nasal lavage fluids. The levels of TAME-esterase activity and albumin were significantly less during exposure to hot, humid conditions compared to normal or cold, dry environments. The other parameters were also less, although they did not reach statistical significance. We conclude that the temperature and humidity of inspired air affect the immediate allergic response. The mechanism for this reduction needs to be elucidated.