Biomedical subjects
F W Ruscetti
Publications and source records attributed to F W Ruscetti.
Evaluation of hematopoiesis in long-term bone marrow culture: comparison of species differences.
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Bone marrow toxicity induced by oral benzo[a]pyrene: protection resides at the level of the intestine and liver.
The Ah locus encodes a cytosolic receptor that regulates the induction of certain drug-metabolizing enzymes by polycyclic aromatic hydrocarbons such as benzo[a]pyrene. Some inbred mouse strains such as C57BL/6N have the high-affinity Ah receptor (Ahb/Ahb), others such as DBA/2N, the poor-affinity receptor (Ahd/Ahd). Presence of the high-affinity receptor leads to greater cytochrome P1-450 induction by benzo[a]pyrene; in turn, enhanced benzo[a]pyrene metabolism can result in more toxic intermediates or greater detoxication, depending upon the test system studied. Benzo[a]pyrene in the growth medium, in direct contact with cultured myeloid cells, is more toxic to C57BL/6N than DBA/2N cultured cells. Oral benzo[a]pyrene induces P1-450 (measured by benzo[a]pyrene trans-7,8-dihydrodiol formation determined by high-performance liquid chromatography) in C57BL/6N but not DBA/2N intestine and liver. In the bone marrow of oral benzo[a]pyrene-treated C57BL/6N and DBA/2N mice, the magnitude of P1-450 induction is about the same. WB/ReJ (Ahd/Ahd), C57BL/6J (Ahb/Ahb), or (WB/ReJ)(C57BL/6J)F1 (Ahb/Ahd) marrow was transplanted into lethally irradiated (WB/ReJ)(C57BL/6J)F1 mice. DBA/2J (Ahd/Ahd) marrow was transplanted into lethally irradiated BALB/cByJ (Ahb/Ahb) mice and vice versa. Mice having the Ahd/Ahd intestine and liver died in less than 3 weeks of benzo[a]pyrene feeding (120 mg/kg/day), irrespective of the source of transfused marrow. All the data are consistent with pharmacokinetic differences in the tissue distribution of benzo[a]pyrene: mice having the high-affinity receptor, and therefore the P1-450 induction process in the intestine and liver, are protected from oral benzo[a]pyrene-induced myelotoxicity.
Persistent in vitro infection by human T-cell leukemia-lymphoma virus (HTLV) of normal human T-lymphocytes from blood relatives of patients with HTLV-associated mature T-cell neoplasms.
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Inhibition of differentiation and proliferation of colony-stimulating factor-induced clonal growth of normal human marrow cells in vitro by retinoic acid.
Necessary for growth and differentiation in many normal tissues and capable of inducing differentiation in human promyelocytic cell lines, retinoids were the subject of this study. Specifically, effects of 13-cis-retinoic acid and 13-trans-retinoic acid on the growth of normal human bone marrow cells in soft-agar system were studied. Both short-term incubation and continuous exposure to retinoic acid caused a decreased number of granulocyte colonies and an increased cluster-to-colony ratio. This effect was concentration-dependent. Examination of specimens stained with Wright-Giemsa or nitro blue tetrazolium stains showed a progressive increase in the percentage of immature granulocytic precursors with increasing concentrations of retinoic acid. No effect of retinoic acid was seen on a number of human tumor cell lines. Retinoic acid blocked both differentiation and proliferation and appeared to do so by specific, noncytotoxic mechanisms in normal human bone marrow cells.
Restricted expression of integrated primate type-C virus (gibbon ape leukemia virus-simian sarcoma virus) proviral DNA in nonproductively infected human B lymphoblasts.
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Human T-cell leukemia-lymphoma virus (HTLV) is in T but not B lymphocytes from a patient with cutaneous T-cell lymphoma.
A human type C retrovirus, designated HTLV, previously was isolated from or identified in some patients with leukemias and lymphomas of mature T lymphocytes. HTLV is genetically and serologically distinct from any known animal retroviruses. The absence of HTLV proviral sequences in DNA from normal humans showed that HTLV is not a ubiquitous endogenous (germ-line transmitted) virus of humans. Antibodies to HTLV core proteins have been identified in some people with T-cell neoplasias and are particularly prevalent in Japanese with adult T-cell leukemia, suggesting that HTLV is acquired horizontally. However, it was possible that HTLV is transmitted through the germ line of some (possibly rare) families and is then expressed in the HTLV- positive malignancies. An opportunity to study this question was provided by the development of several T-cell lines and a B-cell provided by the development of several T-cell lines and a B-cell line from one HTLV-positive patient with a cutaneous T-cell lymphoma. Here we report that HTLV proteins or nucleic acids (or both) are found in three independently derived T-cell lines, all shown by HLA typing to have originated from the patient. In contrast, the B-cell line, the identity of which was also ascertained by HLA typing, contained no detectable HTLV protein, RNA, or proviral DNA. Because the sensitivity of the latter assay is more than sufficient to detect one proviral equivalent per haploid genome, the results indicate that HTLV was not transmitted to this patient through the germ line but rather was acquired by infection.
Human trophoblasts: cellular source of colony-stimulating activity in placental tissue.
Colony-stimulating activity (CSA) is a class of protein factors that stimulates the in vitro growth and differentiation of hematopoietic committed stem cells into mature granulocytes and macrophages. In man, production of CSA is mediated by monocytes-macrophages, lymphocyte, and endothelial cells. One of the best studied and most potent sources of CSA is conditioned media derived from cultured human placenta. The cellular source of this placental CSA was studied using cloned term placental cell lines induced by a simian virus 40 (SV-40) Wild-Type (wt) or temperature sensitive (tsA) mutants. Conditioned media from SV-40 wt-transformed placental cells grown at 37 degrees C and tsA-transformed placental cells grown at 33 degrees C (the temperature at which the cells exhibit the transformed phenotype) and at 40 degrees C (temperature at which the cells express a normal differentiated phenotype) contained high levels of CSA. At the restricted temperature (40 degrees C), these cell lines expressed normal trophoblastic characteristics in that they produced human chorionic gonadotropin, pregnancy-specific-beta1-glyco protein, and placental alkaline phosphatase, indicating that the SV-40 transformation has not interfered with normal cellular functions of these trophoblasts. The CSA released by these cell lines resemble those of CM from fresh placental cells, in that the level of activity is high and that formation of both granulocyte/macrophage and eosinophil colonies is stimulated.
Induction of differentiation of HL-60 cells by dimethyl sulfoxide: evidence for a stochastic model not linked to the cell division cycle.
Induction of differentiation of human promyelocytic leukemia cell line HL-60 by dimethyl sulfoxide (Me2SO) was analyzed to determine the relationship between exposure time of the inducer and cell cycle. A minimum incubation time of 12 hr with Me2SO was required in order to induce differentiation in a small but significant proportion of cells. These expressed differentiation markers (morphology, phagocytosis, and nitroblue tetrazolium reduction) up to 12 hr after Me2SO was removed from the medium. For periods beyond 12 hr and as long as 120 hr of contact of HL-60 cells with the inducing agent, a linear rise in the percentage of differentiated cells was observed. The sensitivity to Me2SO of HL-60 cells synchronized by double thymidine block was examined and was found to be similar to that of nonsynchronized cells. The effect of Me2SO was not altered when incubated with cells at different phases of the cell cycle. Finally, even nonproliferating cells were sensitive to the inducing effect of Me2SO. The data are consistent with a stochastic model of induction to differentiation without having any linkage to the cell cycle.
Terminal differentiation of the human promyelocytic leukemia cell line, HL-60, in the absence of cell proliferation.
Induction of differentiation of the human promyelocytic leukemia cell line, HL-60, by dimethyl sulfoxide was analyzed for a requirement for cell replication. The ability of HL-60 cells to undergo terminal granulocytic differentiation as judged by nitroblue tetrazolium reduction, phagocytosis, and morphological criteria was not impaired by a total block in cellular proliferation. Retinoic acid, actinomycin D, and butyric acid also induced differentiation of HL-60 cells in the absence of cell growth. These results and the earlier demonstration that phorbol ester-induced macrophage differentiation of HL-60 occurred independently of DNA synthesis indicate that in these leukemic cells there is a dissociation of proliferation and maturation. The ability of retinoic acid to enhance differentiation of HL-60 cells was not altered in the presence of various growth-inhibiting concentrations of two clinically useful chemotherapeutic agents: hydroxyurea and 1-beta-D-arabinofuranosylcytosine. These results suggest that combination therapy in a program aimed at both inhibiting proliferation and inducing differentiation of leukemia cells could be beneficial.
Factors that affect human hemopoiesis are produced by T-cell growth factor dependent and independent cultured T-cell leukemia-lymphoma cells.
Some laboratory results and clinical situations suggest that human T cells may be important in the regulation of growth of hematopoietic cells. Since the discovery of T-cell growth factor (TCGF), systems are now available for the long-term specific in vitro propagation of mature normal or neoplastic human T cells, providing an opportunity to study the influence of T cells on hematopoiesis. Recently, 24 cell lines from patients with cutaneous T-cell lymphoma (CTCL) and T-cell acute lymphoblastic leukemia (T-ALL) were grown with TCGF and then assessed for release of humoral factors that affect hematopoiesis. Conditioned media (CM) from these cell lines were tested for erythroid burst-promoting activity (BPA) and granulocyte colony-stimulating activity (CSA). BPA was detected in CM from 3/6 cultures of T-ALL patients and 4/6 CTCL cultures. CSA was found in the CM from 6/8 cultures of T-ALL patients, 7/12 CTCL cultures, and 3/4 CTCL cell lines that become independent of exogenous TCGF for growth. The CSA from several of the neoplastic T-cell cultures stimulated high levels of eosinophil colonies, a possible source of the eosinophilia seen in these patients. The ability of continuously proliferating human T lymphocytes, which retain functional specificity and responsiveness to normal humoral regulation, to produce factors that directly or indirectly stimulate myeloid and erythroid colony formation lends further credence to the role of T lymphocytes in regulating hematopoiesis.
A biochemical variant of human T cell growth factor produced by a cutaneous T cell lymphoma cell line.
Three cell lines of mature T cell origin established from patients with cutaneous T cell lymphoma-leukemia (CTCL) have been found to be constitutive producers of TCGF (L-TCGF). Biologically active L-TCGF can also be eluted from the plasma membranes of these cells. We have compared the biologic and biochemical properties of L-TCGF and TCGF derived from normal lymphocytes (N-TCGF). L-TCGF and N-TCGF share similar biologic activity: both support long-term growth of T cells that have undergone prior lectin or antigen stimulation, and have no effect on unstimulated T cells. However, L-TCGF is a more acidic (pI 4.5 vs 6.5 to 8.0) molecule than N-TCGF and elutes from DEAE-Sepharose at higher salt concentration (0.2 M NaCl vs 0.07 to 0.1 M NaCl). In addition, these two factors display differing mobilities on gel filtration. Treatment of L-TCGF with neuraminidase or alkaline phosphatase does not alter its pI, indicating that enzymatically vulnerable sialic acid or phosphate groups are not involved in the variation. The nature and significance of this biochemical variant remain unknown.
Presence of mixed colony-forming cells in long-term hamster bone marrow suspension cultures: response to pokeweed spleen conditioned medium.
In contrast to the murine system, long-term hamster bone marrow suspension cultures maintain proliferation of both pluripotent and committed stem cells in the absence of an adherent layer and without addition of exogenous factors, such as hydrocortisone. Addition of pokeweed-mitogen-stimulated hamster spleen conditioned medium (SCM) to these long-term suspension cultures produces an increase in the number of mixed colonies assayed in soft-agar, These mixed colonies, which contained four cell lineages--granulocytic, erythroid, megakaryocytic, and macrophage--could be generated from cells grown in suspension for over 6 mo. Addition of SCM also induces an initial rapid expansion of the myeloid compartment, and this expansion results in 70% of the cells being terminally differentiated granulocytes. In contrast, addition of SCM to hamster bone marrow cultures containing both adherent cells and hematopoietic stem cells produced no change in the number of mixed colonies generated in the culture. This system allows the in vitro study of the process of stem cell proliferation and differentiation and also provides a means to examine the relationship of adherent and supernatant bone marrow populations.
Evaluation of erythropoiesis in long-term hamster bone marrow suspension cultures: absence of a requirement for adherent monolayer cells.
In long-term hamster bone marrow cultures, proliferation and differentiation of hemopoietic stem cells occurs for several months without need for hydrocortisone or adherent stromal elements, which are requirements for bone marrow growth in all other species studied. Only the most primitive erythroid progenitors (BFU-E) are produced in the cultures. Following treatment of the cells with erythropoietin, these progenitor cells undergo differentiation into mature hemoglobinized red blood cells. Concomitant addition of erythropoietin (Epo) and prostaglandin-E1 (PGE1) results in the production of large numbers of maturing red blood cells. In cultures stimulated with Epo and PGE1, as many as 70% of the cells are benzidine-positive, while Epo alone stimulated as many as 45% of the cells to become erythroid. Epo and PGE1 do not have any apparent deleterious effect on the continuous hemopoiesis occurring in these cultures. Under identical conditions, syngeneic adherent cell cultures do not produce any erythroid elements. The development of mature red blood cells from primitive erythroid precursors occurs in the presence of Epo alone and without any apparent need for adherent stromal elements. These cultures provide a useful in vitro model for dissecting the positive and negative signals that regulate erythropoiesis.
Detection of the human T cell lymphoma virus p19 in cells of some patients with cutaneous T cell lymphoma and leukemia using a monoclonal antibody.
A monoclonal antibody specific for the internal p19 protein of a type-C retrovirus (HTLV) isolated from human neoplastic T cells has been developed. Its specificity has been shown by radioimmune precipitation and by affinity chromatography of iodinated HTLV proteins. By indirect immune fluorescence this antibody recognizes only HTLV-producing cells. Examination of cells from patients with cutaneous T cell lymphomas and leukemias and with other types of lymphomas and leukemias indicated that HTLV p19 expression is rare. The monoclonal antibody will be useful in determining the natural reservoir of HTLV, possibly in a subset of mature T cell neoplasias.
Isolation of a new type C retrovirus (HTLV) in primary uncultured cells of a patient with Sézary T-cell leukaemia.
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Human cutaneous T cell lymphoma and leukemia cell lines produce and respond to T cell growth factor.
Three cell lines of mature T cell origin derived from patients with cutaneous T cell lymphoma-leukemias (CTCL) were found to be constitutive producers of T cell growth factor (L-TCGF). These are the first reported human cell lines which constitutively produce TCGF. Biologically active TCGF could also be eluted from the surface of these cells using an acid glycine buffer under conditions that maintained cell viability, and subcellular fractionation showed that almost all the TCGF activity was associated with the plasma membrane. Over 30 other human hematopoietic cell lines derived from other disorders were unable to produce TCGF even after induction, and their acid eluates did not contain TCGF activity. L-TCGF from CTCL lines had the same biological activity as TCGF obtained from normal leukocytes (N-TCGF) in that they both supported the long-term growth of normal T cells only after the cells were previously activated by antigen or lectin. Both L-TCGF and N-TCGF increased the rate of proliferation of TCGF-independent and TCGF-dependent CTCL cell lines. The same three factor-independent cell lines that released TCGF adsorbed TCGF in a cell-concentration, time-, and temperature-dependent manner. Since the CTCL cell lines produce TCGF, adsorb TCGF, and increase their proliferative rate in response to TCGF or a related molecule, it is suggested that this endogenously produced factor plays a role in maintaining the abnormal proliferation of these cells in culture as permanently growing cell lines independent of exogenous TCGF. However, this does not mean that this is an essential aspect of neoplastic transformation. Since it is unusual to develop these cell lines in the absence of the continuous need for added TCGF, "autostimulation" may be one of the many unusual variant phenotypic properties sometimes associated with neoplastic cells that gives them a selective advantage for in vitro growth.
Natural antibodies to the human T cell lymphoma virus in patients with cutaneous T cell lymphomas.
Sera from patients with cutaneous T cell lymphoma and leukemia were screened for the presence of natural antibody to the human T cell lymphoma (leukemia) virus, HTLVCR, using a solid-phase radioimmunoassay. Sera from two patients, including patient CR, from whose cultured T lymphoblastic cell line (HUT102), the retrovirus HTLVCR was isolated, reacted specifically with proteins of HTLVCR. Serum from patient CR also reacted specifically with proteins of HTLVMB, an independent but highly related retroviral isolate from a patient with Sezary T cell leukemia. The specificity for HTLVCR proteins was demonstrated by solid-phase immunocompetition assays and competition radioimmunoprecipitation assays. Analysis of radioimmunoprecipitates indicated that the natural antibodies were directed against HTLVCR core proteins with molecular weights of 24,000 and 19,000 (p24 and p19). Whereas the serum reactivities for HTLVCR proteins were shown to be highly specific, additional reactivities seen against proteins of animal retroviruses including GaLV, SSV, FeLV, and BaEV were clearly shown not to be viral specific but rather were due to reactivity with cellular antigens contaminating the viral preparations or with related antigens present in fetal calf serum. These results demonstrating natural antibodies to HTLVCR provide the first evidence for a specific antibody response to a retrovirus in humans.