Mediator release from rat peritoneal and human lung mast cells as well as human leukemic basophils was examined to determine whether super-oxide (O−2) was concomitantly generated. Immunologic or nonimmunologic stimulation of each preparation induced parallel release of histamine and O−2 within 2 min. O−2 production was quantitated by superoxide dismutase (SOD)-inhibitable chemiluminescence and cytochrome c reduction. SOD was detected in basophil and mast cell lysates and was also released by rat mast cells stimulated by anti-IgE. Secretory granules isolated from purified rat mast cells released histamine, O−2, and SOD upon exposure to cations. Thus, both superoxide radicals and SOD may play a role in host defenses involved in immediate hypersensitivity reactions.
William R. Henderson, Michael Kaliner