Nuclear labelling of leukaemic blast cells with tritiated thymidine triphosphate in 35 patients with acut leukaemia.

A new technique which detects the presence of DNA polymerase and primer-template DNA by measuring the in vitro incorporation of [3H]thymidine-5-triphosphate (3H-TTP) into nuclei of leukaemic blast cells (LBC) was used in 35 patients with acute leukaemia. The 3H-TTP labelling index (3H-TTP LI) exceeded the fraction in DNA synthesis by a factor 1.4-24.3. The values of 3H-TTP labelling in the bone marrow always exceeded those obtained in the blood. In addition 10 normal bone marrows were studied; here, the 3H-TTP LI either exceeded or equalled the fraction of the proliferative pool in DNA synthesis.