Correlations between total protein, lysozyme, immunoglobulins, amylase, and albumin in stimulated whole saliva during daytime.

The correlations between salivary proteins and the daytime variations are not known. The present study investigated the within-subject variation of correlations and concentrations between lysozyme, IgA, IgG, IgM, albumin, amylase, and total protein in stimulated whole saliva of healthy adults in the course of a 12-h period. After several practise sessions, unstimulated and stimulated whole saliva samples were collected five times daily (at 8 a.m., 11 a.m., 2 p.m., 5 p.m., and 8 p.m.) from 30 healthy university students. Flow rate and total protein concentration were used as covariates, and gender as a between-subject factor in the MANOVA analysis. After this adjustment, there was significant within-subject variation in salivary IgA (P < 0.001), albumin (P < 0.01), amylase (P < 0.05), and total protein (P < 0.001) concentrations. Total protein correlated significantly with amylase albumin and IgA through different samplings. In addition, IgG correlated with albumin and lysozyme in the course of 12 h. On the whole, the correlations between variables remained stable during repeated samplings. In addition, rankings of subjects for the variables tended to be maintained across different samplings (P < 0.001). However, the observed within-subject variations in salivary IgA, albumin, amylase, and total protein concentrations suggest that these proteins are subject to short-term variation.