Comparison of salivary IgA secretion rate collected by the aspiration method and swab method.

Salivary immunoglobulin A (IgA) is used as an immunity marker, as saliva can be easily collected, noninvasively with little stress. However, several saliva collection methods can be used. Our comparison between samples collected using different methods demonstrated that the salivary IgA secretion rate in samples collected using an aspiration method was significantly correlated with that in samples collected using a swab method. Moreover, the significant circadian variation in salivary IgA secretion rate in the aspirated saliva suggested that the aspiration method does not suppress salivary IgA secretion rate variability compared with the swab method. Therefore, the aspiration method should be considered as the preferable saliva collection method.