Clinical utility of bone marrow culture.

Standardized culture of bone marrow in soft agar permits the detection of a population of granulocyte-macrophage progenitor cells (CFU-c). A spectrum of qualitative abnormalities serves to distinguish myeloid leukemic CFU-c from normal and remission populations. These abnormalities in maturation and proliferation are diagnostic of a myeloid leukemic state and serve to functionally reclassify acute myeloid leukemia at diagnosis into a number of categories based on in vitro growth pattern. The virtue of this classification is that it permits detection of a substantial number of patients who are refractory to conventional remission induction protocols. The clear distinction between normal and leukemic growth in vitro permits early detection of emerging remission CFU-c during induction therapy and of early onset of relapse in patients who are otherwise in complete remission. In patients with leukemia undergoing allogeneic bone marrow engraftment, marrow culture has proved of value in documenting the reconstitution of the patient and in detecting re-emergence of the original leukemic stem line prior to its detection by cytogenetic and hematological techniques. Serial studies on patients with chronic myeloid leukemia have allowed early diagnosis of blastic transformation and classification of blastic phase disease on the basis of in vitro growth pattern has revealed a similar spectrum of in vitro abnormalities as seen in AML. The cloning of normal or leukemic human myeloid progenitor cells (CFU-c) in agar or methylcellulose has permitted analysis of both quantitative and qualitative changes in this cell compartment in leukemia and other myelodysplastic states (1-7). Among these changes are abnormalities in maturation of leukemic cells in vitro (4, 5, 6), defective proliferation as measured by colony size or cluster to colony ratio (5, 6), abnormalities in biophysical characteristics of leukemic CFU-c (4, 5), regulatory defects in responsiveness to positive and negative feedback control mechanisms (8, 9) and the existence of cytogenetic abnormalities in vitro (10, 11). Detection of this spectrum of abnormalities has proved of clinical utility in diagnosis of leukemia and preleukemic states (5, 6, 12), in classification of leukemias and myeloproliferative diseases (5, 6), in predicting remission prognosis and response to therapy (5, 13), in predicting onset of remission or relapse in AML (13) and in monitoring the progression of chronic myeloid leukemia or preleukemic disease (4, 14). The present communication serves to illustrate the clinical applications of bone marrow culture in these various areas.