Bone-marrow-profileration patterns in acute myeloblastic leukaemia determined by pulse cytophotometry.

The proliferation patterns of normal and leukaemic bone-marrow were studied by measuring the D.N.A. content of large numbers of cells by pulse cytophotometry (P.C.P.). In nineteen normal bone-marrow samples an average of 66-3% of the bone-marrow cells were in the G1 phase (2n D.N.A.), 26-1% in the S phase (2n smaller than D.N.A. smaller than 4n), and 7-5% in G2+M phase (4n D.N.A.). The percentages of S-phase cells determined by autoradiography and P.C.P. correlated well, both in normal and in leukaemic bone-marrow. In 25 patients with untreated acute myeloblastic leukaemia (A.M.L.) lower percentages of cells were found in S and G2+M phases, indicating a smaller proliferating pool compared with normal bone-marrow. The likelihood of a complete remission being attained in A.M.L. with the first treatment course was correlated with the percentage of S-phase cells present before treatment. At remission in A.M.L. the proliferation pattern was restored to normal.