Burst-promoting activity in anemia and polycythemia

Clinical erythrokinetics: a critical review

The hemoglobin concentration and the hematocrit percentage are usually used to diagnose anemias and erythrocytoses and to monitor their treatment and progress. However, they may be misleading because of dehydration or dilution and it is imperative to keep in mind their relationship to the size of the red-cell mass. This size is determined by the cellular kinetics of four distinct compartments which make up the erythron: the stem cells, the progenitor cells, the precursor cells and the mature cells. Under normal physiologic conditions, the kinetics of the progenitor-cell compartment determines the size of the red-cell mass but, under abnormal conditions, the kinetics of each of the compartments may affect the size. In this review, normal and abnormal kinetics of the four compartments are defined and related to the size of the red-cell mass and the pathogenesis of anemias and erythrocytoses.

Spontaneous cytokine overproduction by peripheral blood mononuclear cells from patients with myelodysplastic syndromes and aplastic anemia

We studied spontaneous cytokine production by peripheral blood mononuclear cells (PBMC) obtained from 14 patients with aplastic anemia (AA) and 28 various myelodysplastic syndromes (MDS). The levels of interleukin-6, interleukin-1 beta, and tumor necrosis factor-alpha in cultured PBMC were measured by ELISA. The average levels of these cytokines were higher in AA or in refractory anemia (RA) than in RA with excess of blasts (RAEB) or in RAEB in transformation (RAEB-T). Marked cytokine overproduction was observed in RA as well as in AA. High cytokine levels were observed in hypocellularity and low blast cell counts in the bone marrow. These results may suggest that the increase of cytokines may be a reactive response in hypocellular bone marrow.

Binding properties and proliferative effects of human recombinant granulocyte-macrophage colony-stimulating factor in primary leukemia and lymphoma

Binding of radiolabeled human granulocyte-macrophage colony-stimulating factor (GM-CSF) was studied with blast cells from eight patients with acute myeloblastic leukemia (AML), and neoplastic lymphoid cells from one patient with acute lymphoblastic leukemia (ALL), two patients with chronic lymphocytic leukemia (CLL) and one patient with undiagnosed B cell neoplasia. In all AML cases studied, Scatchard graphs of the direct binding data were curvilinear, and were best fitted by curves derived from a two-binding-site model; one site with high affinity (Kd1 = 12-71 pM; 174-602 sites/cell) and the other with low affinity (Kd2 = 0.5-2.7 nM; 1137-6020 sites/cell). A cross-linking study on blast cells from one AML patient demonstrated specific bands which were similar to those reported for peripheral blood neutrophils. Furthermore, blast colony assays for the same preparations showed remarkable proliferative response to GM-CSF in the concentration range from 0.3 nM to 7.0 nM (ED50 greater than 0.7 nM). This concentration range is approximately one order of magnitude higher than that which is effective for colony formation from normal bone marrow progenitors (ED50 in equilibrium 0.1 nM). No significant correlation could be observed between the responsiveness of blast progenitors to GM-CSF, and the numbers or affinities of GM-CSF binding sites demonstrated on blast cells. In studies with neoplastic lymphoid cells from four patients, 125I-GM-CSF also specifically bound in two cases, while response to GM-CSF was not observed in these cases. These results indicate that the expression of GM-CSF receptor is not restricted to the GM-CSF-responsive AML blast cells, but can be observed in other AML blast cells and even in neoplastic lymphoid cells.