Can AMP induce sputum eosinophils, even in subjects with complete asthma remission?
BACKGROUND
The definition of "clinical asthma remission" is based on absence of symptoms and use of medication. However, in the majority of these subjects airway inflammation is still present when measured. In the present study we investigated whether "complete asthma remission", additionally defined by the absence of bronchial hyperresponsiveness (BHR) and the presence of a normal lung function, is associated with the absence of airway inflammation.


METHODS
Patients with a former diagnosis of asthma and a positive histamine provocation test were re-examined to identify subjects with complete asthma remission (no asthma symptoms or medication, PC20 histamine > 32 mg/ml, FEV1 > 90% predicted). Patients with PC20 histamine < or = 32 mg/ml were defined as current asthmatics and were divided in two groups, i.e. asthmatics with and without BHR to adenosine 5'monophoshate (AMP). Sputum induction was performed 1 week before and 1 hour after AMP provocation. Sputum induction and AMP provocation were previously shown to be sensitive markers of airway inflammation.


RESULTS
Seven patients met criteria for complete asthma remission. Twenty-three were current asthmatics, including twelve without hyperresponsiveness to AMP. Subjects with complete asthma remission showed no AMP-induced sputum eosinophilia (median (range) 0.2 (0 - 4.6)% at baseline and 0.2 (0 - 2.6)% after AMP). After AMP, current asthmatics had a significant increase in sputum eosinophils (0.5 (0 - 26.0)% at baseline and 2.6 (0 - 32.0) % after AMP), as had the subgroup of current asthmatics without hyperresponsiveness to AMP (0.2 (0 - 1.8)% at baseline and 1.3 (0 - 6.3)% after AMP).


CONCLUSIONS
Subjects with complete asthma remission, in contrast to subjects with current asthma, do not respond with eosinophilic inflammation in sputum after AMP provocations. These data lend support to the usefulness of the definition of complete asthma remission.
Volbeda
Franke
F
Department of Pulmonology, University Medical Center Groningen, University of Groningen, The Netherlands.
ten Hacken
Nick H T
NH
Lodewijk
Monique E
ME
Dijkstra
Antoon
A
Hylkema
Machteld N
MN
Broekema
M
M
Timens
Wim
W
Postma
Dirkje S
DS
D000249:Adenosine Monophosphate; D000328:Adult; D000368:Aged; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D005541:Forced Expiratory Volume; D006632:Histamine; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012074:Remission Induction; D013183:Sputum / Q000166:cytology / Q000276:immunology*; D016896:Treatment Outcome
D018927:Anti-Asthmatic Agents; D000249:Adenosine Monophosphate; D006632:Histamine