Ultrastructural defects of respiratory tract cilia associated with chronic infections.

Ultrastructural defects were demonstrated in nasal and bronchial cilia from a 12-year-old boy with repeated upper and lower respiratory tract infections. Numerous abnormalities were found, including single axonemes surrounded by excess cytoplasmic matrix, compound cilia, intracytoplasmic microtubular doublets, and cilia contained within a periciliary sheath. Dynein arms were missing from the majority of the peripheral microtubular doublets. The most striking abnormality, however, was a disorientation of cilia as judged by the increased variation in the orientation of central microtubules. Because of these ultrastructural abnormalities, it is highly likely that ciliary motility was markedly decreased and that defective mucociliary transport was responsible for chronic and repeated upper respiratory tract infections.