Increased nitric oxide production in the respiratory tract in asymptomatic pacific islanders: an association with skin prick reactivity to house dust mite.
BACKGROUND
Exhaled nitric oxide (NO) is increased in asthma and may also be increased in subclinical airway inflammation. The relationship between atopy and subclinical airway inflammation in the pathogenesis of asthma remains unclear. We have evaluated the relationship between exhaled NO levels and skin prick test reactivity to 8 common allergens in 64 asymptomatic adult Pacific Islanders. Pacific Islanders were studied as a racial group with major morbidity from asthma.


OBJECTIVE
Our purpose was to determine whether asymptomatic subjects with skin prick test reactivity to common allergens have elevated NO levels.


METHODS
All subjects underwent full lung function testing and skin prick testing. Exhaled and nasal NO levels were measured by chemiluminescence (Logan LR2000 analyzer) with use of the single-breath and breath-holding techniques, respectively.


RESULTS
House dust mite (HDM) reactivity was seen in 38 of 64 (56%). Exhaled NO levels (median 8.9 ppb, range 2.9-47.3 ppb) and nasal NO levels (527.5 +/- 181.5 ppb) lay above the normal European range in 30% and 25% of subjects, respectively. HDM reactivity was associated with higher exhaled NO levels (P <. 0005) and higher nasal NO levels (P =.01). In HDM-sensitive subjects the wheal size for HDM correlated with exhaled NO levels (r = 0.35, P =.04) and nasal NO levels (r = 0.40, P =.01). On multivariate analysis, exhaled NO levels were independently and positively related to the severity of HDM reactivity (P =.01) and nasal NO levels (P <.02), equation R(2) = 0.27.


CONCLUSIONS
NO levels are elevated in a significant proportion of asymptomatic Pacific Islanders and are associated with HDM sensitivity. This may denote subclinical airway inflammation in this population and suggests that exposure to HDM in atopic individuals might play an important role in the early pathogenesis of asthma.
Moody
A
A
Respiratory Services and the Department of Otolaryngology, Green Lane Hospital, the Department of Medicine, School of Medicine, University of Auckland, New Zealand.
Fergusson
W
W
Wells
A
A
Bartley
J
J
Kolbe
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000485:Allergens; D000818:Animals; D001249:Asthma / Q000208:ethnology / Q000209:etiology / Q000276:immunology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D008925:Mites / Q000276:immunology; D009569:Nitric Oxide / Q000096:biosynthesis*; D010139:Pacific Islands; D044469:Racial Groups; D012137:Respiratory System / Q000378:metabolism*; D012882:Skin Tests
D000485:Allergens; D009569:Nitric Oxide