Immunological parameters in Down syndrome children with and without recurrent lower respiratory tract infections

Abstract

Background: Immunological abnormalities are since long described in Down syndrome (DS) children. The clinical relevance, however, is still unclear.

Aim: To compare immunological parameters in DS children with and without recurrent lower respiratory tract infections (RRTI).

Methods: We prospectively collected blood samples in a cohort of DS children to determine white blood cell count and differentiation, lymphocyte subsets and immunoglobulin A, G and M levels. Additionally, we collected information about individual infectious burden from patient files.

Results: To date, 54 patients have been included with an even distribution in gender, almost all of them have free trisomy 21, two mozaicism. Mean age at time of sampling was 6.3 years (range 0 to 17). Twenty-two children (40.7%) suffered from RRTI. In this subgroup, there is a tendency in higher leukocyte count (p=0.09) and significantly higher neutrophil count (p=0.046) compared to those without RRTI. When comparing flow cytometry results, there is a small difference in double negative T-cells (known for their role in regulating immunological and inflammatory homeostasis) (p=0.066), not in the other investigated cell populations. No differences were found concerning levels of IgG, IgA or IgM. Statistical analyses were corrected for age.

Conclusions: While several immunological parameters in DS differ from controls, we found no significant dissimilarities when comparing DS children with and without RRTI’s besides a higher neutrophil count. We suggest studies with larger study populations and/or different markers which could help to explain the immunological impact on infectious burden in DS children.