Salivary IgA concentration is influenced by the saliva collection method.

Measurement of salivary IgA is useful for the non-invasive assessment of secretory immunity, especially in children and infants. In our study, the influence of three commonly used methods ("spitting", "suction", "Salivette") of saliva collection on the yield of salivary IgA concentration was analysed in 54 samples of salivary secretion collected from six healthy children according to a cross over protocol. Nephelometrically determined IgA concentrations were significantly lower in saliva collected by the Salivette device (mean +/- SEM: 23 +/- 7 mg/l) than in saliva collected by the suction (46 +/- 8 mg/l) or spitting method (48 +/- 8 mg/l). Salivary flow assessed by the spitting method was inversely correlated with salivary IgA concentration. We conclude that salivary IgA assessment is influenced by the saliva collection method, and that studies dealing with this topic should accurately describe the methods used for collecting saliva so that data may be properly compared.