Humoral immunity in root caries in an elderly population. 2

Saliva specimens stored for 18 months at -20 degrees C with or without glycerol and the anti-protease benzamidine-HCl, lost all antibody activity for S. mutans. IgA activity in processed whole saliva decreased significantly after one week when stored either at 4 degrees C or -20 degrees C with or without glycerol, although it was stable in parotid saliva for at least 40 days. Loss of activity prior to processing was significant in the first 24 h, and the addition of 50% glycerol and storage at -70 degrees after processing, prevented loss of antibody activity in both whole and parotid saliva. Diurnal variations in IgA, lactoferrin and the IgA secretion rate were insignificant in parotid saliva but showed some fluctuations in whole saliva. Albumin and lactoferrin levels exhibited the greatest fluctuation in whole saliva specimens although IgA and IgA antibody levels were still more characteristic of the patient than the time of sampling. Monthly variations in IgA, IgA antibody activity and other parameters were least in parotid saliva and e.g., values for parameters that were high in patients samples on the first month, remained high during the 4-month study period. Statistical analyses showed a high correlation between values obtained for most of the 15 parameters that were measured in parotid and whole saliva specimens collected from greater than 20 patients during 2 successive visits. Whole saliva values for albumin, lactoferrin and albumin levels in parotid saliva, were most variable but differences were not significant. Hence, patients with very low or very high values, even in whole saliva, can be identified within the population on the basis of specimens collected at a single time.