Nasal ciliary function and ultrastructure in Down syndrome.

OBJECTIVES/HYPOTHESIS: To investigate the in vivo nasal ciliary beat and the ciliary ultrastructure in Down syndrome because, although in this condition an increased susceptibility to respiratory tract infections has been reported by several authors, the nature of this phenomenon is not fully understood.

STUDY DESIGN

Experimental study of 18 subjects with Down syndrome and 18 healthy control subjects.

METHODS

Ciliary beat frequency (CBF) was measured on samples of ciliated epithelium obtained from the inferior nasal turbinate; a further brushing for ultrastructural analysis was performed only in subjects showing a CBF reduction or a ciliary movement alteration.

RESULTS

The mean CBF in the group with Down syndrome was 7 +/- 2.82 Hz, and in the control subjects it was 10.94 +/- 0.65 Hz. In the same 66.6% of subjects with Down syndrome, we observed a fibrillatory movement of cilia and no metachronicity was present. Moreover, in 14 subjects with Down syndrome as hyperproduction of mucus was present. Ultrastructural evaluation at transmission election microscopy instead revealed a normal architecture of cilia.

CONCLUSION

We attribute the nature of the mucociliary defect in Down syndrome to recurrent respiratory tract infections causing changes in mucus properties as in rheological parameters and not to a primitive defect of cilia.