Correlation between IgA antibody and eosinophil cationic protein levels in induced sputum from asthmatic patients.
BACKGROUND
Eosinophils are known to be main effector cells in allergic inflammation and IgA antibody has been shown to be a potent stimulus for eosinophil degranulation in in vitro conditions.


OBJECTIVE
To evaluate the possible role of IgA antibodies on eosinophil degranulation in lower respiratory mucosa of asthmatics, we tried to find a correlation between total IgA and eosinophil cationic protein (ECP) levels in induced sputum from asthmatics.


METHODS
We measured total IgA and albumin levels by nephelometry, and eosinophil cationic protein levels by Pharmacia CAP system in induced sputum from 23 atopic asthmatics and 12 healthy controls.


RESULTS
IgA and albumin levels in induced sputum from asthmatics with sputum eosinophilia (sputum eosinophil count > or = 5% of 200 counted non-squamous cells) were significantly higher (P < 0.05) than those from controls. However, IgA and albumin levels in induced sputum from asthmatics without sputum eosinophilia were not significantly different with those from controls (P > 0.05). In induced sputum from asthmatics, ECP levels were significantly correlated with albumin (r = 0.44, P = 0.04) and IgA levels (r = 0.67, P = 0.002). ECP/albumin ratio was also significantly correlated with IgA/ albumin ratio (r = 0.61, P = 0.004).


CONCLUSIONS
Our results support the hypothesis that IgA antibodies in tracheobronchial secretion may be involved in eosinophil degranulation in asthma, and further study is needed to prove this hypothesis.
Nahm
D H
DH
Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea.
Park
H S
HS
D000328:Adult; D000418:Albumins / Q000032:analysis; D001249:Asthma / Q000276:immunology*; D001798:Blood Proteins / Q000032:analysis*; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000737:chemistry*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis*; D018836:Inflammation Mediators / Q000032:analysis*; D008297:Male; D009391:Nephelometry and Turbidimetry; D012260:Ribonucleases; D013183:Sputum / Q000737:chemistry*
D000418:Albumins; D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D007070:Immunoglobulin A; D018836:Inflammation Mediators; D012260:Ribonucleases