Airway eosinophilia and expression of interleukin-5 protein in asthma and in exacerbations of chronic bronchitis.
BACKGROUND
An increased number of eosinophils in the bronchial mucosa has been demonstrated both in asthma and in exacerbations of chronic bronchitis.


OBJECTIVE
To investigate whether the airway eosinophilia present in asthma and in chronic bronchitis during exacerbations is associated with interleukin (IL)-5 protein expression in the bronchial mucosa.


METHODS
We obtained bronchial biopsies in 18 subjects with asthma (four intrinsic, seven extrinsic and seven occupational) and in 11 subjects with chronic bronchitis examined during an exacerbation. The findings were compared with those of bronchial biopsies from 10 subjects with chronic bronchitis examined under baseline conditions and from seven normal subjects, taken as controls. By immunohistochemistry, we assessed the expression of IL-5 protein and the number of eosinophils (EG2), mast cells (tryptase), and T-lymphocytes (CD3) in the submucosa.


RESULTS
As compared with controls, the number of eosinophils was increased to a similar degree in both asthma (P < 0.001) and in exacerbations of chronic bronchitis (P < 0.001), whereas the number of IL-5 immunopositive cells was increased significantly only in asthma (P < 0.01). No differences were observed in the number of mast cells and T-lymphocytes between the four groups of subjects examined.


CONCLUSIONS
This study shows that the degree of airway eosinophilia is similar in asthma and in exacerbations of chronic bronchitis, but only in asthma is it associated with an increased expression of IL-5 protein in the bronchial mucosa.
Saetta
M
M
Institute of Occupational Medicine, University of Padova, Italy.
Di Stefano
A
A
Maestrelli
P
P
Turato
G
G
Mapp
C E
CE
Pieno
M
M
Zanguochi
G
G
Del Prete
G
G
Fabbri
L M
LM
D000328:Adult; D000368:Aged; D001249:Asthma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001706:Biopsy; D001991:Bronchitis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001999:Bronchoscopy; D002908:Chronic Disease; D004802:Eosinophilia / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007150:Immunohistochemistry; D015848:Interleukin-5 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
D015848:Interleukin-5