Increased incidence of urethan-induced lung adenomas in neonatally thymectmized mice challenged with lymphoid cells.

Neonatally thymectomized uretha~-treated Swiss mice inoculated repeatedly with competent lymphoid cells from the same random-bred strain developed a higher incidence of lung adenomas than that observed in thymectomized urethantreated controls. The immunologic impairment and pathologic findings noted in the inoculated animals were more severe than those observed in neonatally thymectomized controls, suggesting the development of a graft-versus-host reaction induced by the repeated inoculation of the competent cells. Thymectomized controls inoculated with kidney cells or with in vitro irradiated spleen cells showed neither an increased lung adenoma incidence nor the clinical picture of a graft-versushost reaction.