INTERACTION BETWEEN X-IRRADIATED PLATEAU-PHASE BONE MARROW STROMAL CELL LINES AND CO-CULTIVATED FACTOR-DEPENDENT CELL LINES LEADING TO LEUKEMOGENESIS IN VITRO.

The present studies indicate that x-irradiation of bone marrow stromal cells induces changes that are registered in a co-cultivated hematopoietic cell population. The data provide evidence that leukemogenesis by x-irradiation may be an indirect process involving a primary event in cells of the bone marrow stroma. While these data need to be confirmed by other studies, the possibility that x-irradiation leukemogenesis in fact is an indirect event. These data may have relevance for bone marrow transplantation in which leukemia recurrence in the donor cell population has been documented in several clinical studies. One interpretation of such clinical observations in the light of the present data is that donor hematopoietic stem cells co-cultivated with irradiated recipient stromal cells might have led to an indirect leukemogenesis through primary event in the host's stromal cell microenvironment.