HOT, HUMID AIR PARTIALLY DECREASES THE RESPONSE TO NASAL CHALLENGE WITH ANTIGEN

Allergic rhinitis affects individuals in multiple environmental settin gs. We hypothesized that the environmental conditions of temperature a nd humidity had no effect an the early response to nasal challenge wit h antigen. To test this hypothesis, we selected 16 subjects with aller gic rhinitis and challenged them intranasally with either ragweed or g rass antigen after they were acclimatized for 1 hour in an environment al chamber to the following conditions: 4 degrees C and 30% relative h umidity (RH) (cold and dry environment), 22 degrees C and 50% RH (norm al indoor environment), and 37 degrees C and 90% RH (hot and humid env ironment). The subjects remained in the chamber and were challenged wi th three increasing doses of antigen. Their response was measured by c ounting 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 fluid;. The levels of TAM E esterase activity and albumin were significantly less during exposur e to hot, humid conditions compared to normal or cold, dry environment s. The other parameters were also less, although they did not reach st atistical 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.