Immunologic and nonimmunologic generation of superoxide from mast cells and basophils.

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.