Immunomodulation by nitrite inhalants may predispose abusers to AIDS and Kaposi's sarcoma.

Epidemiological studies indicating that nitrite inhalant abuse is a co-factor in HIV infection and in Kaposi's sarcoma are supported by recent experimental studies, described in this review. Inhalation exposure to the nitrites produce a nonspecific cytotoxicity, depleting many cells of the immune system. Apparently distinct from this cytotoxicity, inhalation of the nitrites impairs a variety of immune mechanisms, affecting both humoral and cell-mediated immunity. In addition, the inhalant-increased macrophage production of the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), can directly stimulate HIV replication and can also stimulate the growth of Kaposi's sarcoma cells. Thus, nitrite inhalants may impair immune resistance to infection and actively promote viral replication and tumor growth.