Am. J. Respir. Crit. Care Med.,
Volume 157, Number 6, June 1998, 1900-1906
Repeated Aerosol Exposure to Small Doses of Allergen
A Model for Chronic Allergic Asthma
S.
HASAN ARSHAD,
ROBERT G.
HAMILTON,
and
N.
FRANKLIN ADKINSON Jr.
Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University School of Medicine,
Baltimore, Maryland
To improve our understanding of the pathophysiology of chronic allergic asthma, we mimicked natural allergen exposure by giving tiny doses of dust-mite extract (equivalent to estimated daily exposure in a typical bedroom) in three weekly sessions for 4 wk. Nine mild asthmatic adults who were
highly sensitive to dust-mite allergen participated in the study. Serial assessments of bronchial reactivity by methacholine challenge, pulmonary function, symptoms, and bronchodilator requirements
were obtained. Seven of nine subjects had a twofold or more (median: 6, range: 2.7 to 25) reduction (p = 0.008) in PC20, after which saline inhalations were substituted for dust-mite extract. Bronchial
reactivity returned to normal within 2 to 3 wk after cessation of dust-mite inhalations in all but one
subject. Predosing FEV1 dropped 10% over 4 wk of provocation (p = 0.001) and 7 of 9 returned to prestudy level within 2 wk after dosing was stopped. Late-phase responses were seen in 6 of 9 subjects.
We conclude that repeated aerosol exposure to dust-mite allergen in doses comparable to natural
bedroom exposure is sufficient to adversely affect pulmonary function and bronchial hyperractivity in
sensitized individuals. These changes are rapidly reversible. This low-dose provocational strategy provides an attractive model for the experimental study of allergic asthma. Arshad SH, Hamilton RG,
Adkinson NF, Jr. Repeated aerosol exposure to small doses of allergen: a model for chronic
allergic asthma.
