Warming of feet elevates nasal mucosal surface temperature and reduces theearly response to nasal challenge with allergen

Background: We have previously shown that hot, humid air partially reduces the early allergic response, Mechanisms for this effect have been suggested , but none has gained universal acceptance. The most likely explanations ar e a modification of mucosal temperature or a reduction in nasal secretion o smolality, Objective: We sought to investigate whether increasing the nasal mucosal su rface temperature by immersing feet in warm water (WW) could decrease the i mmediate nasal response to challenge with allergen. Methods: We performed a randomized, 2-way crossover study on 14 subjects wi th seasonal allergic rhinitis outside of their allergy season. They immerse d their feet in either WW (42 degrees C) or room-temperature water (RW; 30 degrees C) for 5 minutes before and during nasal challenge with diluent for the allergen extract, followed by 2 increasing doses of allergen. Results: There was a statistically significant increase in nasal mucosal:te mperature from baseline after warming of feet (WW, 1.9 +/- 0.1 degrees C, v s RW: 0.2 +/- 0.1 degrees C; P = .001), but there were no significant diffe rences in body temperature (WW, 0.1 +/- 0.1 degrees C, vs RW, 0.4 +/- 0.1 d egrees C; P = .1), Net changes from diluent challenge for all parameters we re compared between immersion of feet in WW and RW, Immersion of feet in WW significantly: inhibited allergen-induced sneezes (WW, 5.7 +/- 1.1, vs RW, 11.6 +/- 3.2; P < .01), human serum albumin levels (WW, 941.7 +/- 172.2 mu g/mL vs RW, 1524.8 +/- 220.6 mu g/mL; P < .01), and secretion weights (WW, 30.5 +/- 7.2 mg, vs RW, 41.8 +/- 6.8 mg; P < .01). Conclusion: Our data show that warming of feet decreases the early response to nasal challenge with antigen. This inhibitory effect is probably relate d to the increase in the nasal mucosal temperature.