The role of autoantigens and that of target organs in which tissue lesions develop remains elusive in most spontaneous models of autoimmune diseases. Whether the presence of target autoantigens is required for the recruitment of autoreactive lymphocytes is unknown in most cases. To evaluate the importance of islet cells in the development of autoimmunity in the nonobese diabetic (NOD) mouse, we generated beta cell-deprived mice by injecting a high dose of alloxan, a toxic agent specific for beta cells. In contrast with spleen cells from 6-mo-old naive NOD mice which transfer diabetes in irradiated 8-mo-old male recipients, spleen cells from age-matched NOD mice which received a single injection of alloxan at 3 wk of age did not transfer diabetes. With the exception of the ability to transfer diabetes, beta cell-deprived NOD mice showed maintained immune competence. Furthermore, sialitis developed with the expected intensity and prevalence in beta cell-deprived mice. Already committed "diabetogenic" spleen cells collected from spontaneously diabetic mice also showed a reduced capacity to transfer diabetes after their removal from the diabetic mice and transient "parking" in beta cell-deprived mice. Taken together, our data bring evidence that involvement of autoreactive T cells detected by the capacity to transfer diabetes requires the presence of target beta cells.