RESUMO
The increased clinical use of total lymphoid irradiation (TLI) as an immunosuppressive adjunct in transplantation suggested the need for determining the effects of TLI on the in vivo susceptibility of animals to infections controlled by cell-mediated immunity. TLI-treated, TLI-treated and splenectomized, and chimeric mice prepared with TLI were inoculated in the hind foot pad with Mycobacterium marinum or Mycobacterium leprae. Although M. marinum organisms multiplied in greater numbers in the TLI mice, ultimately they were destroyed as effectively in TLI mice as in the non-irradiated control mice. M. leprae multiplied at the same rate and to the same maximum in TLI mice as in controls. Mice previously challenged with M. marinum in one hind foot pad, and challenged subsequently with the same organism in the opposite hind foot pad, showed a solid immunity against this reinfection. It appears that upon recovery from the immediate effects of radiotherapy TLI-treated mice are able to mount an effective immune response to experimental infection with M. marinum and M. leprae.