Table 1.

Study Inclusion and Exclusion Criteria

	Inclusion Criteria	Exclusion Criteria
Subjects with allergic rhinitis and asthma	Age 18–55 yr	Current use of antihistamines, nasal steroids, LTRA, or tiotropium
	Clinical diagnosis of asthma	Current symptoms of rhinitis
	Positive skin prick test to timothy grass pollen (in a panel of 10 aeroallergens)	Smoking history in the past 6 mo
	Histamine PC20 < 8 μg/ml (or <12 μg/ml and bronchodilator response ≥12%)	History of clinically relevant systemic disease or respiratory disease (other than asthma)
	Daily ICS (daily dose ≥400 μg fluticasone or equivalent) or ICS and LABA	OCS treatment in the previous 3 mo
	ACQ score > 0.75	Pregnant or breastfeeding women
Healthy subjects	Age 18–55 yr	Smoking history in the past 6 mo
	PC20 > 8 μg/ml and bronchodilator response <12%	Positive skin prick test
		History or current symptoms of atopic disease such as allergic rhinitis, asthma, or eczema
		Shortness of breath at screening
		History of respiratory or significant systemic disease
		Use of ICS or OCS in the previous 3 mo
		Current use of LABA, nasal spray, antihistamine, LTRA, or tiotropium
		Pregnant or breastfeeding women

Definition of abbreviations: ACQ = Asthma Control Questionnaire, ICS = inhaled corticosteroid; LABA = long-acting β₂ agonist; LTRA = leukotriene receptor antagonist; OCS = oral corticosteroid; PC₂₀ = concentration of histamine required to reduce FEV₁ by 20%.