Induction of unscheduled DNA synthesis in human bone marrow cells by bifunctional alkylating agents.

A technique has been developed for handling human bone marrow cells intended for the examination of DNA repair synthesis. DNA-repair synthesis, induced by melphalan and nitrogen mustard, was measured as the incorporation of 3H-thymidine, registered by autoradiography as unscheduled DNA synthesis (UDS). Comparison of various cell populations disclosed considerable differences in their UDS level, this generally being greatest for the blast populations. During maturation of both myelopoietic and erythropoietic cells, there was a decrease in the UDS level, which was lowest for the end-cell stage. The lymphocytes and monocytes differed considerably in their capacity for UDS. The developed technique would appear to offer an opportunity for determining the capacity for DNA-repair synthesis in malignant bone marrow cells, a factor that has been linked to sensitivity to alkylating agents.