Premature chromosome condensation studies in human leukemia: 4. Characterization of albumin density fractionations of bone marrow at presentation, remission, and relapse.

Previous studies have suggested that the technique of premature chromosome condensation (PCC) is useful in the study of human leukemia, both as a predictive tool for course of disease and as a probe to better understand the biology of the disease process. The purpose of this study was to determine how the various subcomponents of bone marrow populations contribute to the overall PCC pattern. Thirty bone marrow aspirations from persons at various stages of disease (2 normal, 11 untreated, 12 in remission, and 5 n relapse) were fractionated according to density in albumin gradients, and the various fractions were characterized by determining the proliferative potential index (PPI, or the fraction of G1 cells in late G1) using the PCC technique. In general, normal bone marrow and marrow from patients In remission showed lower PPI values throughout the gradients, with the most dense and most mature cells yielding the lowest PPI values in the gradient. In contrast, bone marrow from newly presenting patients and from patients in relapse showed higher PPI values, with the highest PPI values found In the most dense fractions containing the most mature cells. Thus, residual mature cells from patients with active disease exhibit the malignant characteristic of accumulating in late G1 phase. It is postulated that these morphologically mature cells from patients with active disease either represent matured cells of malignant origin or represent residual normal cells pushed beyond the restriction point in early G1 phase by a putative tumor growth factor synthesized by the leukemic cell population.