Phagocytic function in Down syndrome--I. Chemotaxis.

Defects in host defences may provide a partial explanation for the increased incidence of infection in individuals with Down syndrome. Neutrophil and monocyte cellular and humoral chemotaxis were evaluated to explore phagocytic function. Fourteen individuals with Down syndrome and fifteen matched institutionalised controls were studied. In addition, a non-matched comparison normal group was investigated, representing a non-institutionalised young adult population. Neutrophil chemotaxis in institutionalised individuals (both Down syndrome and matched controls) was significantly impaired. Monocyte chemotaxis in this group was lower than in comparison normals. Evaluation of humoral components of neutrophil chemotaxis revealed no significant differences between individuals with Down syndrome and those with no known chromosomal abnormality. Down syndrome subjects had diminished humoral monocyte chemotactic responses compared with institutionalised controls and normal subjects.