Organ specificity of c-kit(+) lymphoid precursors in the liver, thymus, and bone marrow

c-kit(+)Lin(-) cells are present in various immune organs, including the li ver, thymus, and bone marrow, where lymphoid, myeloid, or erythroid cells a re generated. To compare their properties as lymphoid precursors, c-kit(+)L in(-) cells purified from various organs of B6.Ly5.1 mice were injected int o 6.5 Gy-irradiated B6.Ly5.2 mice. Depending on the source of the c-kit(+) cells, the degree of entrance and expansion of lymphoid cells differed in t he liver and thymus of recipient mice. c-kit(+) cells isolated from the bon e marrow entered and expanded prominently in both the liver and thymus, whe reas c-kit(+) cells from the thymus did not do so at all. On the other hand , c-kit(+) cells isolated from the liver and spleen showed an intermediate pattern, namely, they took a long time to enter and expand in the liver and thymus of recipient mice. All of these c-kit(+) cells had the potential to give rise to lymphoid cells, which were specific to the liver and thymus, respectively. We previously showed that progenitor cells for extrathymic T cells in the liver and those for conventional T cells in the thymus are not always supplied by the bone marrow, as shown by experiments using parabios is. Taken together with those previous data, the present results suggest th at c-kit(+)Lin(-) cells isolated from various immune organs have organ spec ific properties.