ELEVATED TNF-ALPHA AND INDUCIBLE NITRIC-OXIDE PRODUCTION BY ALVEOLAR MACROPHAGES AFTER EXPOSURE TO A NITRITE INHALANT

Abuse of nitrite inhalants, widespread among male homosexuals, has bee n identified by epidemiological studies as an independent risk factor for AIDS and for Kaposi's sarcoma, Subchronic exposure of mice to inha led isobutyl nitrite was previously found to impair the tumoricidal ac tivity of peritoneal macrophages, Because inhalants would be expected to have the greatest effects on cells in the lung, alveolar macrophage s from exposed mice were examined in this study, Mice were exposed to 900 ppm isobutyl nitrite in an inhalation chamber for 45 min/day for 1 4 days. Following this treatment, the lungs of exposed mice had large increases in cellularity, both in the alveolar septa and within the al veoli, Bronchoalveolar lavages also contained increased numbers of cel ls, Alveolar macrophages collected from treated mice had increased tum oricidal activity compared with controls and produced higher levels of inducible nitric oxide and tumor necrosis factor-alpha (TNF-alpha). T he frequency of alveolar cells secreting TNF-alpha was increased ninef old in mice exposed to the inhalant. Cell influx into the lung, as ind icated by the presence of red blood cells in lung lavages, was evident after only a single 45-min exposure to inhaled isobutyl nitrite at do ses as low as 300 ppm.