Identifying superoxide-sensitive progenitor cells in mouse bone marrow.

Macrophage progenitor cells in bone marrow, that develop into attached colonies in liquid culture medium, contain a fraction of cells sensitive to photochemically generated superoxide radicals. This fraction varies from one animal to another. Populations of cells containing the superoxide-sensitive fraction show a greater sensitivity to X-rays than do populations in which this fraction has been photochemically inactivated. The change in radiosensitivity was proportional to the superoxide-sensitive fraction.