Hot, humid air increases cellular influx during the late-phase response to nasal challenge with antigen

Clin Exp Allergy. 2001 Dec;31(12):1913-22. doi: 10.1046/j.1365-2222.2001.01271.x.


Background: Inhalation of hot, humid air (HHA: 37 degrees C, > 95% relative humidity (RH)) partially inhibits the early response to nasal challenge with antigen.

Objective: To investigate whether HHA inhibited the late-phase response to nasal challenge with antigen and increased hyper-responsiveness of the nasal mucosa to histamine.

Methods: Twenty subjects with seasonal allergic rhinitis, outside of their allergy season, participated in a randomized, 2-way cross-over study. The subjects continuously breathed room air (25 degrees C, 30% RH) or HHA delivered via a face mask during the entire experiment. Subjects were challenged intranasally with antigen 1 h after beginning conditioning. The response was monitored by symptoms and nasal lavage at 2-h intervals after the last antigen challenge. Eight hours after antigen challenge, nasal challenge with histamine was performed.

Results: Exposure to HHA significantly increased nasal mucosal temperature from baseline without affecting nasal secretion osmolality. HHA significantly inhibited antigen-induced sneezes, congestion, pruritus, and human serum albumin levels during the early response to antigen challenge. HHA exposure, however, was associated with an 8-fold increase in the eosinophil influx and a 15-fold increase in the levels of eosinophil cationic protein during the late-phase response compared to room air. There were no significant differences in nasal hyper-responsiveness to histamine during either exposure.

Conclusion: HHA partially decreases the early response to nasal challenge with antigen, but dramatically increases eosinophil influx. Increasing eosinophil number had no effects on the hyper-responsiveness to histamine. We speculate that the physical conditions of air differentially impact the stages of allergic inflammation.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Air*
  • Antigens / immunology*
  • Antigens / pharmacology*
  • Atmosphere Exposure Chambers
  • Blood Proteins / drug effects
  • Blood Proteins / metabolism
  • Cross-Over Studies
  • Eosinophil Granule Proteins
  • Female
  • Histamine / immunology*
  • Histamine / pharmacology*
  • Hot Temperature
  • Humans
  • Humidity*
  • Leukocytes / drug effects
  • Leukocytes / immunology
  • Leukocytes / metabolism
  • Male
  • Nasal Lavage Fluid / chemistry
  • Nasal Lavage Fluid / cytology
  • Nasal Mucosa / chemistry
  • Nasal Mucosa / physiopathology
  • Nasal Provocation Tests*
  • Reaction Time / drug effects*
  • Reaction Time / immunology*
  • Rhinitis, Allergic, Seasonal / etiology
  • Rhinitis, Allergic, Seasonal / physiopathology
  • Ribonucleases*
  • Serum Albumin / drug effects
  • Serum Albumin / immunology
  • Serum Albumin / metabolism
  • Time Factors


  • Antigens
  • Blood Proteins
  • Eosinophil Granule Proteins
  • Serum Albumin
  • Histamine
  • Ribonucleases