Phagocytic cell activity and periodontitis in Down syndrome

Background: This study investigated the phagocytic function of peripheral granulocytes and monocytes from adult individuals with Down syndrome (DS) and assessed the relation between phagocytic function and periodontal status. Methods: Fifty-five DS individuals (18-56years old), 74 mentally retarded individuals, and 88 medically healthy controls (HC) participated in the study. Gingival inflammation index, plaque index, probing depth, periodontal attachment level (AL), and bleeding on probing were taken for each subject. Whole blood was collected for granulocyte/monocyte phagocytosis tests. Phagocytic function was determined by flow cytometry in terms of percentage of cells actively involved in phagocytosis, and phagocytic intensity (magnitude of the bacterial staining per cell). Results: Phagocytic intensity of both granulocytes and monocytes was comparable in HC and DS subjects. While AL was directly related to phagocytic intensity of both granulocytes (r=0.14, P=0.03) and monocytes (r=0.2, P=0.003) in all subjects, this relationship was stronger in DS than in other subjects, even after controlling for known risk factors for periodontitis (P<0.05). Monocyte phagocytic intensity was the only necessary predictor of AL (P=0.003), indicating a similar relationship between AL and phagocytic activity in either cell type. Conclusions: While granulocyte and monocyte phagocytic intensities are similar in Down and non-DS individuals, phagocytic intensity was associated with more AL in DS than non-DS individuals.