Nasal ciliary function and ultrastructure in Down syndrome

Objectives/Hypothesis: To investigate the in vivo nasal ciliary beat and th e ciliary ultrastructure in Down syndrome because, although in this conditi on an increased susceptibility to respiratory tract infections has been rep orted by several authors, the nature of this phenomenon is not fully unders tood. Study Design: Experimental study of 18 subjects with Down syndrome an d 18 healthy control subjects. Methods: Ciliary beat frequency (CBF) was me asured on samples of ciliated epithelium obtained from the inferior nasal t urbinate; a further brushing for ultrastructural analysis was performed onl y in subjects showing a CBF reduction or a ciliary movement alteration. Res ults: 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 met achronicity was present. Moreover, in 14 subjects with Down syndrome as hyp erproduction of mucus was present, Ultrastructural evaluation at transmissi on election microscopy instead revealed a normal architecture of cilia, Con clusion: We attribute the nature of the mucociliary defect in Down syndrome to recurrent respiratory tract infections causing changes in mucus propert ies as in theological parameters and not to a primitive defect of cilia.