The transition of sputum inflammatory cell profiles is variable in stable asthma patients.
BACKGROUND
The sputum inflammatory cell profile is an important indicator for classifying asthma phenotypes.


OBJECTIVE
To investigate if sputum inflammatory cell profile remains stable and there are different characteristics between groups that show different profile over time in stable asthmatic patients.


METHODS
A total of 149 asthmatic patients, who were clinically stable at the time of sputum examination and had undergone sputum analysis twice, were subjected to a detailed review. Eosinophilic inflammation was diagnosed when the proportion of the sputum eosinophils was >3%. We divided the patients into 4 groups according to the transition patterns of their sputum profiles: group 1, persistent eosinophilia; group 2, eosinophilic to noneosinophilic; group 3, noneosinophilic to eosinophilic; and group 4, persistent noneosinophilia. The results of the pulmonary function tests and other clinical parameters were compared between these 4 groups.


RESULTS
Thirty-four of the initially eosinophilic asthmatic patients (39.5%; 34 of 86 patients) demonstrated noneosinophilic airway inflammation at their second sputum examination, and 24 of the initially noneosinophilic patients (38.1%; 24 of 63 patients) demonstrated eosinophilic airway inflammation at follow-up. Various clinical parameters, except the blood eosinophil count, demonstrated no significant differences between the eosinophilic and noneosinophilic asthmatic patients or among the 4 groups.


CONCLUSIONS
A substantial proportion of asthmatic patients who demonstrate a certain sputum inflammatory cell profile at the initial examination demonstrated profile transition in clinically stable settings over time. The clinical significance of using induced sputum analysis to phenotype stable asthmatic patients requires further evaluation.
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Bomi
B
Shin
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Hyouk-Soo
HS
Kwon
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
So Young
SY
Park
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Tae-Bum
TB
Kim
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Hee-Bom
HB
Moon
Division of Allergy and Clinical Immunology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
You Sook
YS
Cho
Asthma; Eosinophils; Phenotype; Sputum inflammatory cell