Inhaled isobutyl nitrite compromises T-dependent, but not T-independent, antibody induction.

Habitual abuse of nitrite inhalants has been linked in epidemiological studies with seropositivity to human immunodeficiency virus and, separately, with Kaposi's sarcoma among AIDS patients. Mice exposed to isobutyl nitrite in an inhalation chamber for 45 min/day for 14 days had depressed IgM and IgG antibody responses. The inhibition was dose-dependent at 750-900 ppm, but antibody responses were increased at an intermediate (600 ppm) dose. Gender differences in immunotoxicity were not observed. Antibody responses to a T-independent antigen (DNP-ficoll) were not affected by the immunotoxic exposure, suggesting that B-cells were refractory to the toxic exposure. Toxic exposure to isobutyl nitrite did not selectively deplete a particular spleen cell population, but caused equivalent reductions of T-cells and B-cells. Finally, exposed mice remained immunocompromised for 3-5 days after terminating exposures. Normal immune responses returned by 5-7 days, suggesting that inhibition of cellular function was reversible.