Utility of density gradient centrifugation for fractionation of leukemic bone marrow

Comparison of the distribution pattern of leukemic and normal bone marrow cells, obtained by density gradient centrifugation, may give information about the location of the blockade in the differentiation pathway from stem cell to mature leukocyte, as is supposed to exist in acute leukemia. As a control group 12 children with acute lymphoblastic leukemia (ALL), in complete remission and after cessation of all antileukemic therapy, were studied. By centrifugation over a discontinuous bovine serum albumin (BSA) density gradient, good reproducibility of the partition of the bone marrow cell population was obtained, with a peak in the more dense region. The cells capable of incorporation of [3H] thymidine in vitro were present predominantly in the lower density range. In 9 patients with lympho- or myeloproliferative malignancies (3 with o-cell ALL, 2 with T-cell malignant lymphoma, 1 with B-cell malignant lymphoma, 3 with various malignancies of the myeloid-monocytoid series) similar fractionation on the BSA gradient revealed a different cell partition pattern as compared with the control group. The peak of the distribution curve was located in the less dense region. Highest [3H] thymidine incorporation values were measured in vitro with cells from the lower density region. At last the importance of purely practical considerations in the choice of material for density gradient fractionation is stressed. Application of density gradient centrifugation methods could probably be helpful in attributing to cells from acute leukemia a place in the normal differentiation pathway.