Genetic analysis of in vitro leukemogenesis induced by thymus epithelial reticulum cells transmitting murine leukemia viruses.

Lymphatic leukemia developed in C57BL/6 mice following inoculation of normal thymocytes that and been co-cultured on leukemic thymus epithelial reticulum monolayer cells. Using thymocytes genetically marked in Ly membrane antigens, we showed that the thymomas which developed were produced by the co-cultured thymocytes rather than by leukemic cells derived from the monolayer. Thus, leukemogenic conversion of normal thymocytes took place in vitro. Inoculation of cultured leukemic thymus epithelial reticulum monolayer cells (LTER) gave rise mainly to reticulum cell sarcomas and myeloid leukemias, rather than to lymphatic leukemias (which developed following inoculation of thymocytes that had been cultured on the LTER monolayers). Thus LTER cells may themselves be tumor cells capable of producing RCNA (reticulum cell neoplasm type A) or myeloid tumors in addition to their ability to convert normal thymocytes into leukemic cells.