Age Dependent Deficiency of Salivary Antibodies Secretion in Down's Syndrome

Down's syndrome (DS) individuals suffer from an increased susceptibility to infections in the mucosal respiratory and gastrointestinal systems, including the oral cavity. Objectives: to assess the status and age-related changes of the specific acquired salivary mucosal immune system (MIS) of DS patients. Methods: Parotid and whole saliva were collected from 30 young (YDS) and 10 elderly (EDS) DS individuals (mean age 23.3±4 and 51.9±8 years, respectively). Salivary levels of IgA antibodies against three common oral pathogens (Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Streptococcus mutans) were determined by ELISA and compared to two age-matched groups of healthy volunteers. Results: DS individuals had a severe reduction of the flow rates of whole and parotid saliva. Age had no effect on the salivary flow rate in healthy individuals. In contrast, a significant age-related flow rate reduction was observed in whole and parotid saliva of DS individuals. Secretion rates of bacterial specific antibodies were significantly decreased in YDS compared to healthy controls and in EDS compared to YDS. In contrast, antibodies secretion rates were similar or higher in saliva from elderly compared to young controls. Consequently, a dramatic cumulative extreme reduction (> 94%) in the bacterial specific salivary antibodies secretion rate differentiated the elderly DS individuals from their age-matched controls. Conclusions: A severe immunodeficiency in the response of the specific acquired salivary MIS in DS individuals has been demonstrated. This deficiency, which intensifies with age and is more conspicuous in whole saliva, is apparently unique to DS and might provide a partial explanation for the high rate of recurrent infections in the mucosal system notable in these patients. Our study further suggests that DS individuals, in particular elder ones, may be candidates for immunotherapeutic intervention. This investigation was supported by Dr. Izador Cabakoff Research Endowment Fund.