Reduced activity of Candida detachment factors in the saliva of the elderly.

Saliva in healthy human subjects contains protenaceous factors that detach Candida albicans cells from plastic plates. To investigate the physiological role of the detachment activity of human saliva, we compared the activity of salivary specimens collected from the elderly (who are at greater risk of oral candidiasis) to the activity of specimens collected from children and nonelderly adults. C. albicans cells were cultured and attached to the bottoms of the wells of a 96-well plate, and saliva preparations were then added to each well. After 3 h of incubation, Candida cells attached to the bottoms of the wells were counted, using the crystal violet staining method. The results showed that the activity of salivary detachment factors was significantly lower among the elderly than among nonelderly adults and children. Furthermore, the activity of salivary detachment factors was reduced in 12 of the 43 elderly subjects (27.9%), a significantly higher proportion relative to that in the children and nonelderly adults. However, there was no significant difference in the level of salivary proteins between the samples collected from elderly subjects displaying low and high salivary detachment activity. These results suggest that the increased number of people with lower salivary detachment activity among the elderly may be one of the reasons that oral candidiasis is more common among the elderly than in nonelderly adults and children.