It is probable that the coexistence of two factors is necessary for the development of leukemia in the C57BL mouse exposed to total-body irradiation. The first factor is destruction, followed by regeneration, of thymic lymphocytes. The second factor is the postirradiation environment which provides circumstances such that the regeneration of the thymic lymphocytes becomes uncontrolled, leading to the development of leukemia.

Testosterone, by inhibiting the regeneration of thymic lymphocytes after radiation injury, removes one of the two essential factors, thereby reducing the incidence of leukemia in irradiated C57BL mice.


Supported by an Institutional cancer grant of the American Cancer Society to the University of Colorado and a grant from the Hematology Research Foundation, Chicago.

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