[Secretory immunoglobulin A in childhood: does the saliva value reflect the bronchial value?]

Immunoglobulin A (IgA) can be found in different body secretions and plays a major role in the local immune response. It inhibits bacterial adherence, neutralizes toxins and protects the mucosa from penetrating antigens and allergens. Whereas measurement of IgA in saliva mostly does not show any problems, difficulties in assessing IgA in bronchial fluids often occur mainly due to variable dilutional effects. Aim of the present study was to find out whether saliva IgA predicts bronchial IgA. In 15 children aged 4 months to 14 years (mean 53.5 months; SEM 12.3) with chronic cough (n = 10), mediastinal mass (n = 1), recurrent airways obstructions (n = 2) and inspiratory stridor (n = 2) we performed a diagnostic rigid bronchoscopy and assessed IgA by means of bronchial lavage (BL). We attempted to control for uncertain dilution by the use of albumin as a denominator and to present our data as ratios of IgA to albumin. As various disease states alter the integrity of the alveolar-capillary membrane and influence the concentration of albumin in the epithelial lining fluid we developed an optical score to describe the state of the bronchial mucosa. Measurement of saliva IgA is easy and can be done without dilutional effects. The mean value of IgA in saliva was 65.49 mg/l (SEM 14.75; range 3.5-227), the one of IgA in bronchial lavage fluid 30.75 mg/l (SEM 7.11; range 3.5-100). IgA-albumin ratio ranged from 0.006 to 1.46 (mean 0.36, SEM 0.12). Saliva IgA did neither significantly correlate with bronchial IgA nor with bronchial IgA-albumin ratio.(ABSTRACT TRUNCATED AT 250 WORDS)