[In vitro incorporation of tritiated thymidine in acute leukemia and response to chemotheraphy (author's transl)].

The incorporation of tritiated thymidine (3H-TdR) has been assessed in 52 cases of adult acute leukemia, during the first phase of the disease, before and after 48 hours of chemotherapy. Two methods were utilized simultaneously: the measurement of the incorporation of 3H-TdR by liquid scintillation counting and the labeling index by autoradiography. These two data allowed to appreciate the mean incorporation per labeled blast cell. A significant correlation has been found between liquid scintillation counting and labeling index on the one hand, between mean incorporation per labeled blast cell and mean grain count on the other hand. The prognostic value of these different data was significant, at least if one consider the chance to get a complemente remission with the various drugs which were utilized. The responders are characterized, on the average, by a high rate of incorporation of 3H-TdR before therapy, with a higher labeling index than the non-responders. The measurement of the variations of incorporation of 3H-TdR, 48 hours after starting chemotherapy and before any morphological change, allows an early evaluation of the therapeutic effect: in the responders there is generally a decrease of the 3H-TdR incorporation and of the labeling index. On the apposite in the non-responders there is an increase of the mean incorporation per labeled blast cell, even if the labeling index decreases. The measurement of the incorporation of 3H-TdR by liquid scintillation counting which gives an earlier response than autoradiography, may be considered as a useful prognostic tool in acute leukemia, mainly in the non-lymphoblastic types and during the first phase of the disease.