Accumulation of sestamibi in lymphoma cell lines in vitro.

Although some authors have suggested that sestamibi imaging is useful in evaluation of patients with lymphoma, others have obtained equivocal results. This discrepancy has been further investigated in vitro using two patient-derived non-Hodgkin's lymphoma cell lines, OCI-Ly3 and OCI-Ly18. Sestamibi (0.2 MBq/ml) was added to a suspension of OCI-Ly3 or OCI-Ly18 cells and aliquots were removed over 1 h and centrifuged to determine cell-associated radioactivity. Further experiments studied the effect of addition of a P-glycoprotein (Pgp) modulator or alteration in plasma and/or mitochondrial membrane potentials. Accumulation of sestamibi reached plateau values within 30 min, but these values were 6-fold higher in OCI-Ly3 than in OCI-Ly18. Inhibition of Pgp function with GG918 or PSC833 did not affect OCI-Ly3 cells but increased accumulation in OCI-Ly18 cells 3-fold, indicating a moderate level of Pgp. However, both cell lines responded similarly to membrane potential alterations: hyperpolarization of the mitochondrial membrane with nigericin had little effect on accumulation: in contrast, depolarization of the plasma membrane with an isotonic high potassium buffer reduced accumulation of sestamibi to 52% of control and additional depolarization of the mitochondrial membrane with valinomycin further reduced accumulation to 12% of control levels. These studies suggest that there can be wide differences in accumulation between cell lines, in part due to Pgp-mediated efflux, but that both of these cell lines have highly polarized mitochondria with little further capacity for hyperpolarization.

Nontargeted stable integration of recombinant adeno-associated virus into human leukemia and lymphoma cell lines as evaluated by fluorescence in situ hybridization.

A number of studies on human epithelial cells of varying origin have demonstrated integration of recombinant adeno-associated virus (AAV) vectors into a variety of chromosomes compared with the site-specific integration on chromosome 19 predominantly observed for wild-type (wt) AAV. We have constructed a recombinant AAV (rAAV) vector and tested the integration into hematopoietic cells, using the human acute myeloid leukemia cell line AML5 and the human non-Hodgkin's lymphoma cell line OCI-LY18 as targets. The integration sites were visualized by fluorescence in situ hybridization (FISH). Positive signals were observed for chromosomes 1, 2, 3, 8, 14, 15, 19, and Y. The majority of cells demonstrated integration into one specific site. A minority showed simultaneous integration into more than one chromosome. The frequency of observed integrations was not uniformly distributed among chromosomes; for instance, in AML5 chromosome 2 seemed to be favored. Colony-derived AML5 clones bore unique integration patterns indicating successful transduction of clonogenic progenitor cells with high proliferative potential. The integration was stable and observed for more than 12 months after transduction. FISH has been shown to be a powerful tool for detailed analyses of rAAV integration patterns and can be used to evaluate targets and transduction conditions.

[Hematopoiesis regulation]. / Regulación de la hematopoyesis.

Positive and negative signals are crucial in the regulation of the hematopoietic system. In the last 30 years, more than 20 molecules (glycoproteins) with biological activity upon the hematopoietic progenitor cells and even on the mature blood cells have been purified. The best known of these biomolecules are the hematopoietic growth factors (colony stimulating factors and interleukins), which are able to stimulate bone marrow cells to give mature progeny. At present, not only the sequence of the majority of these glycoproteins and their codifying genes has been determined, but also their target cells and cellular receptors. Research studies of the interaction between the hematopoietic progenitor cells and their stimulating and inhibiting factors are very helpful in the development of clinical trials and have become important tools to explore the origin of a great number of hematological diseases. However, the mechanisms underlying growth/inhibitory factor production and progenitor cell proliferation remain poorly understood.

Regulación de la hematopoyesis. / [Hematopoiesis regulation]

Positive and negative signals are crucial in the regulation of the hematopoietic system. In the last 30 years, more than 20 molecules (glycoproteins) with biological activity upon the hematopoietic progenitor cells and even on the mature blood cells have been purified. The best known of these biomolecules are the hematopoietic growth factors (colony stimulating factors and interleukins), which are able to stimulate bone marrow cells to give mature progeny. At present, not only the sequence of the majority of these glycoproteins and their codifying genes has been determined, but also their target cells and cellular receptors. Research studies of the interaction between the hematopoietic progenitor cells and their stimulating and inhibiting factors are very helpful in the development of clinical trials and have become important tools to explore the origin of a great number of hematological diseases. However, the mechanisms underlying growth/inhibitory factor production and progenitor cell proliferation remain poorly understood.

Pure red cell aplasia in a patient with systemic lupus erythematosus.

Pure red cell aplasia developed in a female patient with systemic lupus erythematosus (SLE). Erythroid colony growth was assessed in semisolid medium culture of bone marrow obtained from a normal donor and cultured in the presence of normal and patient sera. Colony forming units of erythropoiesis and burst forming units of erythropoiesis obtained from a normal donor were inhibited in the presence of patient sera. Our findings support the concept that circulating inhibitors might influence the proliferation of erythroid progenitor cells and erythroid aplasia may be an immunologically mediated syndrome.