Lymphocyte subgroups and recurrent infections in children with Down syndrome - a prospective case control study.

Down syndrome (DS) is the commonest genetic disorder and more liable for recurrent infections. We aimed to determine the differences in lymphocyte subgroups between DS children and the healthy population and to study the pattern and likelihood for recurrent infections and hospital admission due to infection. Our study was carried out in the Genetic Unit of Mansoura University Children's Hospital, Egypt. The study enrolled 150 DS (DS group) and 100 controls (CG group). They were assessed for recurrent infections (including tonsillitis, otitis media [OM], pneumonia, upper respiratory tract infections [URTI], sinusitis, and gastroenteritis [GE]) and hospital admission due to infections. All patients were subjected to complete blood count and flow cytometric analysis for expression markers of B lymphocytes (CD19), natural killer (NK) cells (CD56), and T lymphocytes (CD3, CD4 and CD8). We found a statistically significant increase in the frequency of URTIs and sinusitis, OM, pneumonia, and hospital admission in the DS group. As regards the type of recurrent infection in DS, it was highest for URTIs and sinusitis. For age groups below 13 years, a statistically significant decrease in all studied CD markers was found in the DS group, while for the 13-18-year-olds, a statistically significant decrease was found in CD4, CD19, and CD56 in the DS group. Non-significant correlations were found between CD markers and recurrent infection and hospital admission. We concluded that lymphocyte subgroups that carry CD3, CD4, CD8, CD19, and CD56 were decreased in DS. Recurrent infections and hospital admission are still striking feature for DS but are not significantly correlated with lymphocyte subgroups.