DISCRIMINATION BETWEEN LEUKEMIA AND NON-LEUKEMIA-RELATED CHROMOSOMAL-ABNORMALITIES IN THE PATIENTS LYMPHOCYTES

The inability to measure precancer-related genetic damage accurately i n blood cells of patients with leukaemia or lymphoma has prevented the use in such patients of available biodosimetric methods to determine prior exposure to clastogenic agents. This is because a substantial am ount of disease-related genetic damage appears in the blood cells of t hese patients, thus masking genetic damage that may have been caused p rior to the disease. We describe a new approach that may be used to me asure precancer-related chromosomal aberrations in such patients by to tally separating the affected T lymphocytes from the malignant B lymph ocytes. The approach employs stable chromosome translocations and will detect prior exposures above the detection limit of similar to 0.05-0 .1 Gy. The utility of this approach is illustrated by using blood lymp hocytes from a nuclear dockyard worker who claims his B cell leukaemia was induced by work-related radiation exposures. Blood lymphocytes we re obtained after diagnosis of the disease, but prior to therapy, and measurements were made of the frequency of chromosomal abnormalities i n PHA-stimulated lymphocytes without prior separation of T and B cells and in T lymphocytes after complete separation from B cells using a r esetting technique. Results show that the separation of T cells prior to PHA stimulation eliminates the cancer-related chromosomal damage an d thus appears to facilitate biodosimetry of pre-cancer exposures in s uch patients.