The suppressive influences of human tumor necrosis factors on bone marrow hematopoietic progenitor cells from normal donors and patients with leukemia: synergism of tumor necrosis factor and interferon-gamma.

The influences of human tumor necrosis factor (TNF) (LuKII), recombinant human TNF-alpha, natural human interferon-gamma (HuIFN-gamma), recombinant HuIFN-gamma, and natural HuIFN-alpha were evaluated alone or in combination for their effects in vitro on colony formation by human bone marrow granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells incubated at 5% CO2 in lowered (5%) O2 tension. TNF (LuKII) and recombinant TNF-alpha caused a similar dose-dependent inhibition of colony formation from CFU-GM, BFU-E, and CFU-GEMM. Day 7 CFU-GM colonies were more sensitive than both day 14 CFU-GM colonies and day 7 CFU-GM clusters to inhibition by TNF. BFU-E colonies and CFU-GEMM colonies were least sensitive to inhibition with TNF. The suppressive effects of TNF (LuKII) and recombinant TNF-alpha were inactivated respectively with hetero-anti-human TNF (LuKII) and monoclonal anti-recombinant human TNF-alpha. The hetero-anti-TNF (LuKII) did not inactivate the suppressive effects of TNF-alpha and the monoclonal anti-recombinant TNF-alpha did not inactivate TNF (LuKII). The suppressive effects of TNF did not appear to be mediated via endogenous T lymphocytes and/or monocytes in the bone marrow preparation, and a pulse exposure of marrow cells with TNF for 60 min resulted in maximal or near maximal inhibition when compared with cells left with TNF for the full culture incubation period. A degree of species specificity was noted in that human TNF were more active against human marrow CFU-GM colonies than against mouse marrow CFU-GM colonies. Samples of bone marrow from patients with non-remission myeloid leukemia were set up in the CFU-GM assay and formed the characteristic abnormal growth pattern of large numbers of small sized clusters. These cluster-forming cells were more sensitive to inhibition by TNF than were the CFU-GM colonies and clusters grown from the bone marrow of normal donors. The sensitivity to TNF of colony formation by CFU-GM of patients with acute myelogenous leukemia in partial or complete remission was comparable with that of normal donors. When combinations of TNF and HuIFN were evaluated together, it was noted that TNF (LuKII) or recombinant TNF synergized with natural or recombinant HuIFN-gamma, but not with HuIFN-alpha, to suppress colony formation of CFU-GM, BFU-E, and CFU-GEMM from bone marrow of normal donors at concentrations that had no suppressive effects when molecules were used alone.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro hematopoiesis following induction chemotherapy for acute leukemia.

The treatment of acute nonlymphocytic leukemia results in predictable bone marrow hypoplasia and eventual cellular repopulation. In order to study this postchemotherapy repopulation, assays for hematopoietic progenitor cells were performed on bone marrow samples obtained from seven patients with acute nonlymphocytic leukemia who had received similar chemotherapeutic induction regimens. Burst-forming units (erythrocyte), colony-forming units (megakaryocyte), colony-forming units (granulocyte-macrophage), and colony-forming units (granulocyte-erythrocyte-megakaryocyte-macrophage) were cloned from human bone marrow mononuclear cells 5 and/or 10 days following completion of chemotherapy. All patients were pancytopenic and had hypocellular marrows when studied. Assays were performed 7 to 30 days prior to complete remission. Colony-forming units (granulocyte-macrophage) were equivalent to control values 5 days following chemotherapy, while burst-forming units (erythrocyte) and colony-forming units (granulocyte-erythrocyte-megakaryocyte-macrophage) were not assayable at that time. Ten days following chemotherapy, colony-forming units (granulocyte-erythrocyte-megakaryocyte-macrophage) and colony-forming units (granulocyte-macrophage) were 200 and 250% of normal controls, respectively, while burst-forming units (erythrocyte) were 29% of control values. Colony-forming units (macrophage) were 10 to 15 times normal values 10 days following chemotherapy. In contrast to colonies from normal individuals, those grown from marrow obtained following chemotherapy were frequently macroscopic and were composed of thousands of cells. Patient marrow had larger proportions of progenitor cells in S phase of the cell cycle than did normal controls. These studies suggest the presence of a stem cell in human bone marrow which is resistant to chemotherapeutic agents and has a high capacity to regenerate hematopoietic progenitor cells. The period following completion of chemotherapy for acute nonlymphocytic leukemia appears suitable for the study of the hierarchical nature of human hematopoiesis.

Isolation of human megakaryocytes by density centrifugation and counterflow centrigual elutriation.

Density centrifugation and counterflow centrifugal elutriation were utilized to prepare enriched fractions of megakaryocytes from human bone marrow aspirates. This separation method enriched megakaryocytes in initial marrow aspirates by 116- to 463-fold. Approximately 63% of megakaryocytes were recovered from the initial samples, composing 18.7% of the nucleated cells in the final preparations. Mean megakaryocyte diameters of 51.6 micron and 33.8 micron were obtained from fixed and unfixed cellular specimens, respectively. Smaller platelet glycoprotein-positive mononuclear cells with a mean diameter of 20.5 micron were found in the highest concentrations in this final fraction. These cells presumably represent immature megakaryocytic forms. Counterflow centrifugal elutriation provides a means of isolating enriched populations of marrow megakaryocytes. This accessibility to viable populations of human megakaryocytes will allow additional investigation of the terminal events of megakaryocyte development.