Parallelism between superoxide production of peritoneal exudate cells and lung granulomatous response in mice vaccinated with BCG cell walls

Superoxide enhances the spread of HIV-1 infection by cell-to-cell transmission

Oxidative stress is thought to be involved in the progression of human immunodeficiency virus type 1 (HIV-1)-induced disease. We examined the effect of superoxide (O2-) on HIV-1 spread in cultured human CD4+ cell lines. The O2- significantly enhanced cell-to-cell transmission of HIV-1, although its effect on HIV-1 replication was not evident, presumably due to its cytostatic activity. The effect was notable on the HIV-1 transmission from macrophages to T lymphocytes by endogenous, macrophage-generated O2-. This amplification was specifically reduced to the steady-state level by antioxidants, and further to the basal level by anti-CD4 antibodies, indicating the specificity of O2- for enhancing HIV-1 spread by cell-to-cell transmission.

Amplification of superoxide anion generation in phagocytic cells by HIV-1 infection

Amplification of superoxide (O2-) generation by HIV-1 infection was examined in two human myeloid-monocytic cell lines. The level of O2- generation in HL-60 after infection became significantly higher than that of the steady-state. A similar phenomenon was also shown in U937, but only after acquisition of O2- generation ability by differentiation to macrophages. By means of the NADPH oxidase-coupled responses in infected cells, we reconstituted the O2(-)-generating machinery in cell-free system. The results suggested that cytosolic factor(s) exerted by infection might be responsible for the amplification of O2- generation. Thus, HIV-1 infection could elevate the level of oxidative stress in macrophages which might play an important role in disease progression.