Nasal nitric oxide is reduced in patients with HIV.

The gas nitric oxide (NO) is present in high concentrations in human nasal airways. Since NO is known to inhibit the growth of bacteria and viruses, it has been suggested that airborne NO represents the first line of defence against pathogens in the upper airways. Low nasal NO levels have been reported previously in patients susceptible to upper airway infection. Since HIV-positive patients are at risk for respiratory tract infections, including sinusitis, we studied the levels of NO in the upper and lower airways of these patients. A cross-sectional study with age-matched HIV patients and controls was carried out. Nasal and orally exhaled NO were measured in 31 HIV patients and 26 controls using a well-established chemiluminescence method developed for measurements of gaseous NO in the airways. Nasal NO was 21%, lower (p < 0.05, Student's t-test) in HIV patients than in controls, whereas orally exhaled NO did not differ between the two groups. We conclude that nasal NO is reduced in patients with HIV infection. The reduction in nasal NO may contribute to the decreased resistance to airway infections in these patients.