ACUTE INHALATION EXPOSURE TO ISOBUTYL NITRITE CAUSES NONSPECIFIC BLOOD-CELL DESTRUCTION

Abuse of nitrite inhalants is widespread among male homosexuals and ha s been epidemiologically correlated with seropositivity to human immun odeficiency virus (HIV) and to Kaposi's sarcoma. These drugs may act a s cofactors in AIDS if they compromise the ability to resist infection or tumor growth. We have previously reported that 14 daily 45-minute exposures to 900 ppm isobutyl nitrite in an inhalation chamber did com promise the immunocompetence of mice. We now report that a single 45-m inute exposure produced a transient anemia. Erythrocyte counts, hemogl obin, and hematocrit levels were reduced by 7% but rebounded to above- normal levels 24 hours later. In vitro exposure of blood to isobutyl n itrite vapors did not lyse the cells but did induce Heinz body formati on and increase their binding to macrophages. Thus, it is likely that the red cells were removed by phagocytic clearance, not by direct lysi s. Blood leukocyte numbers were also reduced following a single exposu re to the inhalant, but the cell loss was delayed until 24 hours after exposure. Recovery of peripheral blood leukocytes 72 hours after expo sure coincided with a reduction in spleen cellularity, suggesting that spleen cells were mobilized to replace lost blood leukocytes.