The
secretory immunoglobulin A (
IgA) system plays an important role in the protection of epithelial surfaces. The aim of this study was to evaluate whether the measurement of the primary airway Ig (
sIgA) concentration in bronchial washings is clinically useful in patients with airway epithelial injury or
inflammation. We measured serum
IgA levels and
sIgA concentrations in the bronchial lavages of patients with
chronic bronchitis (n = 10),
bronchiectasis (n = 15),
lung cancer (n = 15) and in healthy control subjects (n = 10). Absolute
sIgA levels of bronchial lavage fluids in the
chronic bronchitis,
bronchiectasis and
lung cancer groups were higher than the controls, but there was no significant difference between the groups.
sIgA/ml recovered bronchial fluid ratios were similar in the all groups. Standardisation of samples by means of
albumin concentration ratios (
sIgA/alb) showed that the bronchial lavages of the patients with
lung cancer,
chronic bronchitis and
bronchiectasis were generally similar and demonstrated a significantly decreased
sIgA/alb ratio compared to that of control subjects (p = 0.001, p < 0.05 and p < 0.05).
sIgA/alb ratios in bronchial lavages recovered from involved lung of the patients with
lung cancer and
bronchiectasis were lower as compared to uninvolved lung (p < 0.001 and p < 0.05). There was no significant difference in serum
IgA levels between all groups. As a result, although our findings seem partly to confirm the hypothesis that local bronchial
IgA secretion is impaired in areas of bronchial epithelial injury or
inflammation, we thought that
sIgA would be useless as a marker of respiratory epithelial injury or
inflammation in patients with
chronic bronchitis,
bronchiectasis and
lung cancer.