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At least 811 records · Page 45Linked to original sources
PubMed2002

Clonotypic myeloma cells able to xenograft myeloma to nonobese diabetic severe combined immunodeficient mice copurify with CD34 (+) hematopoietic progenitors.

The identity of the multiple myeloma (MM) precursor(s) is unknown. Our objective was to determine the myelomagenic capabilities of CD34-enriched autografts. Hematopoietic progenitor fractions from fresh or cryopreserved granulocyte-colony-stimulating factor mobilized blood from myeloma patients were obtained by sorting or enrichment, followed by RT-PCR analysis of clonotypic transcripts and/or their ability to transfer myeloma to immunodeficient mice. CD34(+) enrichment using immunomagnetic methods comparable with those used clinically results in copurification of MM cells able to xenograft nonobese diabetic severe combined immunodeficient mice. Highly purified CD34(+) progenitors from granulocyte-colony-stimulating factor mobilized blood of myeloma patients include, on average, 31% clonotypic MM cells. CD34(+) progenitors also include 31% DNA aneuploid cells. For six of six MM patients, enriched progenitors were myelomagenic as measured by engraftment of clonotypic cells and/or the development of lytic bone lesions. Intrasternal injection of enriched progenitor fractions led to clonotypic cells in the femoral bone marrow and bone lesions at distant skeletal locations, confirming dissemination of myelomagenic cells. MM precursors copurify with normal hematopoietic progenitors, emphasizing the need for tumor-free grafts. Autologous MM engraftment is likely to be considerably more efficient than in a xenogeneic host, strongly suggesting that MM autografts contribute to posttransplant relapse. The xenografting myelomagenic component(s) is unlikely to be plasma cells, given the lack of morphologically identified plasma cells among enriched progenitors. Xenografting MM precursors appear to be CD34(+)CD45(low), similar to normal progenitors. Precursor function within the MM clone seems to be complex and may involve multiple components of the MM hierarchy.

Animals↗
PubMed1991

The immunoregulatory effects of merocyanine 540 on in vitro human T- and B-lymphocyte functions.

Merocyanine 540 (MC 540) is a photoactive dye used to purge bone marrow of tumor cells in autologous bone marrow transplantation. The effects of MC 540 on the lymphoid components in the marrow are unknown. This study evaluates the treatment of lymphocytes by MC 540 (15 micrograms/mL) and light (70 W/m2) on: (1) phytohemagglutinin and Con A-induced proliferation; (2) allogeneic mixed lymphocyte cultures (MLC); (3) the regulation of Ig synthesis by T cells; and (4) the ability of B cells to produce polyclonal Igs as measured by an enzyme-linked immunosorbent assay-plaque assay. The results show that MC 540 and light treatment reduced Con A-stimulated T-cell proliferation greater than 50% after 30 minutes and greater than 80% after 60 minutes of MC 540-sensitized photoirradiation. Ninety minutes of MC 540 and light exposure (designated treatment) inhibited MLC greater than 90%. In polyclonal Ig synthesis, T-cell helper activity could be abrogated by 90 minutes of treatment in cocultures containing untreated B cells. Purified B cells treated for 90 minutes cocultured with normal T cells did not produce Ig. Treatment of B cells completely inhibited Epstein-Barr virus-stimulated Ig synthesis. These data show that T- and B-cell immunity is suppressed by the MC 540-sensitized photoirradiation. Treatment of bone marrow with MC 540 and light may have profound effects on immune reconstitution in autologous marrow graft recipients. More provocative is the fact that the same immunomodulatory effects may be applicable to partially mismatched marrow transplant situations as a means of reducing graft-versus-host reactions.

B-Lymphocytes↗
PubMed1989

Immunophenotypic analysis of clonogenic cells in acute lymphoblastic leukemia using an in vitro colony assay.

A culture system was used to analyze the expression of membrane differentiation antigens on the proliferative or clonogenic fraction of cells from cases of common (precursor B) acute lymphoblastic leukemia (c-ALL). Colonies of leukemic cells were obtained in 18 of 20 cases after 1 week in culture in a liquid layer containing recombinant interleukin-2 (IL-2), phytohemagglutinin (PHA), and B-cell growth factor over an agar feeder layer containing irradiated peripheral blood mononuclear cells plus fetal calf serum (FCS) and horse serum. Cultured cells expressed HLA-DR, CD-9, CD-10, CD-20, and CD-34 antigens, indicating conservation of precursor B phenotype. Differentiation antigen expression on the clonogenic subpopulation giving rise to leukemic colonies was assessed by treating cells prior to culture with selected cytotoxic monoclonal antibodies (MoAbs) and complement or by fluorescence-activated cell sorting. Lytic treatment with HLA-DR, CD-10, CD-9, and CD-20 antibodies produced median reductions in colony formation of 93%, 81%, 73%, and 58% respectively. Combined treatment with CD-9 and CD-10 antibodies produced complete inhibition in 11 of 13 cases. Cell-sorting experiments after CD-10 staining indicated a good correlation with complement lysis studies and also demonstrated that the CD-19 antigen is expressed on a high proportion of clonogenic cells. Colony formation was also significantly reduced in 13 of 17 cases by lytic treatment of cells with the CD-33 antibody MY-9, suggesting expression of this "myeloid" lineage antigen on ALL clonogenic cells. The substantial case-to-case variation in expression of individual differentiation antigens indicates that leukemic cellular heterogeneity is a major consideration in ex vivo bone marrow purging using MoAbs and emphasizes the need for more critical evaluation of purging techniques.

Adolescent↗
PubMed1988

A flexible peptide spacer increases the efficacy of holoricin anti-T cell immunotoxins.

Immunotoxins, constructed by chemically cross-linking an antibody and protein toxin, do not possess the high efficacy of the native toxin. Decreases in toxicity are due in part to the steric constraints imposed on the two macromolecules, which result in both decreased antibody binding and toxin function. In examining the structural features that influence efficacy in holotoxin-antibody conjugates, it was found that the incorporation of a 29-residue polypeptide, derived from the insulin B chain between the antibody and ricin moiety, resulted in an increase in both potency and efficacy. In a murine model system, potency of the peptide spacer conjugate was increased nearly 10-fold; however, when examined by the procedure used to purge bone marrow, the peptide spacer conjugate was not demonstrably more toxic to nontarget cells than the nonspacer conjugate. Thus, in addition to increases of efficacy and potency, this novel immunotoxin demonstrated increased specificity by approximately 10-fold. To test the general utility of peptide spacer inclusion, a T101-ricin conjugate was constructed with the peptide spacer. It yielded a protein synthesis inhibition rate of -0.6 log/h on MOLT-3 cells, greater than 10-fold more efficacious than a previously constructed nonspacer T101-ricin conjugate examined under similar conditions.

Antibodies, Monoclonal↗
PubMed1986

Selective killing of human T-lymphotropic virus-I infected leukemic T-cells by monoclonal anti-interleukin 2 receptor antibody-ricin A chain conjugates: potentiation by ammonium chloride and monensin.

Adult T-cell leukemia is a progressive disease produced by infection of mature T-cells with the human T-lymphotropic virus-I (HTLV-I). These retrovirus infected T-cells express large numbers of receptors for interleukin 2 (or T-cell growth factor). Due to the presence of these receptors, these leukemic T-cells can be selectively killed in vitro by monoclonal anti-interleukin 2 receptor antibody covalently linked to the A chain of the plant toxin, ricin (anti-TAC-A), suggesting that such immunotoxins may be useful in the therapy of this disease. In this report we demonstrate that the lysosomotropic agent ammonium chloride and the carboxylic ionophore monensin substantially potentiate the cytotoxicity of anti-TAC-A on HUT 102 cells, a long-term cultured HTLV-I infected T-cell line. Anti-TAC-A alone produces half-maximal inhibition of protein synthesis in HUT 102 cells at a concentration of 2.2 X 10(-10) M (the 50% inhibitor, concentration). Addition of ammonium chloride or monensin augments the potency of anti-TAC-A killing 100-fold (50% inhibitory concentration = 2.5 X 10(-12) M) and 400-fold (50% inhibitory concentration = 8 X 10(-13) M), respectively; furthermore, these agents accelerate rate of anti-TAC-A intoxication and increase the specific killing of interleukin 2 receptor-bearing leukemic cells. At concentrations which cause only minor harm to colony forming hematopoietic progenitor cells (granulocyte-erythroid, monocytic, megakaryocytic colony forming unit, granulocyte-macrophage colony forming unit, macrophage colony forming unit, and granulocyte colony forming unit), anti-TAC-A alone is able to eliminate greater than 99.99% of an HTLV-I infected T-cell population. In the presence of ammonium chloride or monensin, respectively, a 3.5- and 20-fold greater cytoreduction of HTLV-I infected T-cells is achieved. Combined treatment with anti-TAC-A and monensin may offer an efficient and highly selective means of purging bone marrow of patients with adult T-cell leukemia, which may then be used for autologous marrow transplantation.

Ammonium Chloride↗
PubMed1988

Selective cytotoxicity of an oxygen-radical-generating enzyme conjugated to a monoclonal antibody.

The monoclonal antibody 8A, which recognizes a human plasma cell-associated antigen, was covalently linked to xanthine oxidase in a conjugate maintaining both immunological and enzymatic properties. A significant degree of target cell lysis was obtained at an enzyme concentration that was ineffective on non-target cells and on myeloid staminal cells (CFU-GM). The cytotoxic activity was abolished by an excess of antibody, by allopurinol and by superoxide dismutase and catalase. A possible use of the conjugate for bone marrow purging in multiple myeloma patients is suggested.

Antibodies, Monoclonal↗
PubMed1986

Malignant human B cells express two populations of p24 surface antigens.

Monoclonal antibodies (MoAb) to a leukemia-associated p24 cell surface antigen are currently being used to purge bone marrow of malignant cells before autologous transplantation for acute lymphoblastic leukemia (ALL). Their use as potential diagnostic reagents for hematologic disorders is also under investigation. It has been assumed throughout these investigations that the p24-specific MoAb produced by different laboratories all identify the same antigen. Our present studies indicate that at least two populations of p24 antigens, having different chemical properties and cellular distributions, exist on malignant B cells. For example, eight MoAb raised to ALL cells (ALL-MoAb) identify a p24 antigen on these cells but do not react with the Burkitt's lymphoma cell line Ramos. In contrast, six MoAb raised to Ramos (Ramos-MoAb) identify a p24 antigen on both Ramos and ALL cells. Quantitative binding of both sets of MoAb to ALL cells is comparable. The ALL-MoAb react with platelets, granulocytes, and activated but not resting T lymphocytes, whereas the Ramos-MoAb react with both resting and activated T lymphocytes but not with platelets or granulocytes. The ALL-MoAb react with 11 of 34 human hematopoietic cell lines tested; the Ramos-MoAb react with all 34. Both sets of MoAb react with most of the nonhematopoietic human cell lines tested. Reciprocal exhaustive radioimmune precipitation experiments performed with an ALL cell line indicate that the antigenic determinants recognized by these two sets of MoAb are present on different molecules. Similarly, proteolytic digests of iodinated antigens identified by these two sets of MoAb on ALL cells confirm the unique chemical identities of these molecules and suggest that they reflect the products of different genetic loci. The presence of the antigen identified by the Ramos-MoAb on every cell population tested except granulocytes suggests that it may serve an important cellular function. The existence of two populations of p24 antigens on at least some hematopoietic cells indicates the need for caution when comparing the results of studies of these antigens by groups employing different MoAb.

Animals↗
PubMed1993

Successful pregnancy in a 28-year-old patient autografted for acute lymphoblastic leukemia following myeloablative treatment including total body irradiation.

We report a successful pregnancy in a woman who at the age of 28 years received total body irradiation (TBI; 7.5 Gy) and high-dose chemotherapy prior to autografting of purged bone marrow for acute lymphoblastic leukemia. Four years after transplantation she delivered a healthy girl. Only five previous cases of successful pregnancies are described in the literature after conditioning regimens including TBI. This case shows that restored ovarian function is possible after TBI in spite of prolonged exposure to chemotherapeutic agents during induction and consolidation therapy and relatively high age at the time of transplantation.

Adult↗
PubMed1996

[Treatment of multiple myeloma].

A new era of multiple myeloma management includes new approaches such as genetic marking and gene therapy, immunotherapy, stimulation of graft versus myeloma effect, etc. Intensive clinical research is also focused on the detection of minimal residual disease and bone marrow purging. Clinical trials have begun and the first results are promising, though preliminary. The combinations of new types of therapeutical approaches with the most efficient regimens used until now could form a new type of MM management strategy that better involves minimal residual disease.

Humans↗
PubMed1997

Photodynamic therapy: the clinical perspective. Review on applications for control of diverse tumorous and non-tumorous diseases.

Photodynamic therapy (PDT) is an innovative and attractive modality for the treatment of small and superficial tumours. PDT, as a multi-modality treatment procedure, needs both, a photosensitizer with distinct tumour selectivity and a powerful light source that matches the absorption spectrum of the photosensitizer. The purified haematoporphyrin derivative Photofrin is so far the only sensitizer approved for phase III/IV clinical trials. Major drawbacks of this product are: lack of chemical homogeneity, skin phototoxicity, unfavourable physicochemical properties and poor selectivity in terms of uptake and retention by tumour versus normal cells. Most second generation photosensitizers, including the phthalocyanines, show an increased photodynamic efficiency in the treatment of animal tumours and reduced phototoxic side effects. In 1997, there were more than half a dozen new sensitizers in or about to start clinical trials. To introduce the basic principles of photodynamic therapy, the current review article discusses in some more detail the treatment of endobronchial lung cancer, one of the leading indications of PDT. Moreover, a broad overview is given on the use of PDT for treatment of a wide variety of tumorous and nontumorous diseases, including new strategies for control of rheumatoid arthritis and application of PDT for extracorporeal bone marrow purging.

Animals↗
PubMed2000

Effect of molecular structure on the performance of triarylmethane dyes as therapeutic agents for photochemical purging of autologous bone marrow grafts from residual tumor cells.

Extensively conjugated cationic molecules with appropriate structural features naturally accumulate into the mitochondria of living cells, a phenomenon typically more prominent in tumor than in normal cells. Because a variety of tumor cells also retain pertinent cationic structures for longer periods of time compared with normal cells, mitochondrial targeting has been proposed as a selective therapeutic strategy of relevance for both chemotherapy and photochemotherapy of neoplastic diseases. Here we report that the triarylmethane dye crystal violet stains cell mitochondria with efficiency and selectivity, and is a promising candidate for photochemotherapy applications. Crystal violet exhibits pronounced phototoxicity toward L1210 leukemia cells but comparatively small toxic effects toward normal hematopoietic cells (murine granulocyte-macrophage progenitors, CFU-GM). On the basis of a comparative examination of chemical, photochemical, and phototoxic properties of crystal violet and other triarylmethane dyes, we have identified interdependencies between molecular structure, and selective phototoxicity toward tumor cells. These structure-activity relationships represent useful guidelines for the development of novel purging protocols to promote selective elimination of residual tumor cells from autologous bone marrow grafts with minimum toxicity to normal hematopoietic stem cells.

Animals↗
PubMed1996

Use of a lethally irradiated major histocompatibility complex nonrestricted cytotoxic T-cell line for effective purging of marrows containing lysis-sensitive or -resistant leukemic targets.

Improved marrow purging protocols are needed in autologous bone marrow transplantation (BMT) to achieve complete eradication of minimal residual disease. This study investigates the potential of a human major histocompatibility complex (MHC) nonrestricted killer T-cell line (TALL-104) as a new marrow purging agent in a clinical setting. TALL-104 cells can be irradiated without losing cytotoxic activity against tumor targets in vitro. In vivo, the irradiated killers can be adoptively transferred into immunodeficient and immunocompetent leukemia-bearing mice, and reverse their disease even in advanced stages. The present study shows that gamma-irradiated TALL-104 cells, cultured for 18 hours with marrows from healthy donors, do not impair the viability and long-term growth of committed and pluripotent hematopoietic progenitors. However, as determined by polymerase chain reaction (PCR) and colony assays, TALL-104 cells could completely purge marrows containing up to 50% lysis-susceptible myelomonocytic leukemia cells (U937). When marrows were admixed with a pre-B leukemia cell line (ALL-1), which is fairly resistant to TALL-104 cell lysis in longterm 51Cr-release assays but can be totally growth inhibited by TALL-104 cells in proliferation assays, residual ALL-1 cells were detectable by PCR after TALL-104 purging. However, importantly, these PCR+ marrows were devoid of tumorigenic activity when transplanted into the human hematopoietic microenvironment of human severe combined immunodeficient (SCID) chimeras. These data indicate the strong potential of the TALL-104 cell line in future marrow purging strategies against lysis-susceptible and -resistant leukemias.

Animals↗
PubMed1992

In vitro purging of clonogenic leukemic cells from human bone marrow by heat: simulation experiments for autologous bone marrow transplantation.

In order to apply a simple purging method by heat to autologous bone marrow transplantation (ABMT), we have revaluated the ability to purge clonogenic leukemic cells from the simulated marrow mixture of normal marrow cells and leukemic cell lines (HL-60, Molt-3 and HEL) in vitro by heat, using two different clonogenic assays for normal granulocyte-macrophage progenitors (CFU-GM) and leukemic cell lines. It appeared that in vitro hyperthermia (42 degrees C for 120 min) is able to selectively remove clonogenic leukemic cells from simulated tumor cell-normal marrow mixtures even when leukemic cell concentrations are increased up to 3 x 10(6) cells/ml in vitro, and results in a 4-6 log destruction of clonogenic leukemic cells/ml according to a limiting dilution assay, while leaving half of normal CFU-GM surviving. The hyperthermic purging of clonogenic leukemic cells was not affected in the presence of normal marrow cells in vitro. This high level of clonogenic leukemic cell depletion by heat correlated with that of immunologic and pharmacologic studies. These results suggest that in vitro hyperthermia could be applied effectively and safely for the elimination of residual clonogenic leukemic cells in autologous marrow grafts before ABMT.

Bone Marrow Purging↗
PubMed2004

Activation of protein kinase A (PKA) by 8-Cl-cAMP as a novel approach for antileukaemic therapy.

Activation of PKA by cAMP agonists, such as 8-Cl-cAMP activation, selectively causes rapid apoptosis in v-abl transformed fibroblasts by inhibiting the Raf-1 kinase. Here we investigated whether 8-Cl-cAMP is useful for the treatment of chronic myelogenous leukaemia (CML), which is hallmarked by the expression of the p210(bcr/abl) oncogene. Autologous bone marrow transplantation is a feasible alternative for patients with no suitable donor, but hampered by the risk of relapse due to the persistence of leukaemia cells in the transplant. To study the effects of 8-Cl-cAMP on primary leukaemic cells, bone marrow cells (BMCs) from eight CML patients (one at diagnosis, three in chronic and four in accelerated phase) were treated. Ex vivo treatment of BMCs obtained in chronic phase of CML with 100 microM 8-Cl-cAMP for 24-48 h led to the selective purging of Philadelphia Chromosome (Ph1 chromosome) without toxic side effects on BMCs from healthy donors as measured by colony-forming unit (CFU) assays. BMCs from patients in accelerated phase showed selective, but incomplete elimination of Ph1 chromosome positive colony forming cells. The mechanism of 8-Cl-cAMP was investigated in FDCP-mix cells transformed by p210(bcr/abl), a cell culture model for CML. The results showed that 8-Cl-cAMP reduced DNA synthesis and viability independent of Raf inhibition as Raf inhibitors had no effect. MEK inhibitors interfered with DNA synthesis, but not with viability. In summary, our results indicate that 8-Cl-cAMP could be useful to purge malignant cells from the bone marrow of patients with CML and certain other forms of leukaemias.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Purging with 4-hydroperoxycyclophosphamide.

Over the past 10 years, very-high-dose cytotoxic therapy with rescue of marrow function by autologous bone marrow transplantation (BMT) has been shown to be effective treatment for patients with lymphomas and acute leukemias. However, a major concern has been that infusion of occult tumor cells with the autologous marrow will contribute to relapse. Accordingly, multiple techniques for treating autologous marrow grafts in vitro, to remove or "purge" occult tumor, have been developed. Despite controversy regarding the necessity and efficacy of purging, most autologous transplants for acute leukemia and many for lymphoma are currently purged. Most studies have used immunologic or cytotoxic agents for purging. The most widely used cytotoxic purging agents have been the cyclophosphamide congeners, 4-hydroperoxycyclophosphamide (4-HC) and mafosfamide. Since the first 4-HC-purged autologous marrow transplant was performed in 1980, over 700 patients have received 4-HC-purged autologous bone marrow transplants at Johns Hopkins alone. This review will chronicle the development of 4-HC as a purging agent.

Acute Disease↗
PubMed2001

Autologous bone marrow transplantation for childhood acute lymphoblastic leukemia: a novel combined approach consisting of ex vivo marrow purging, modulation of multi-drug resistance, induction of autograft vs leukemia effect, and post-transplant immuno- and chemotherapy (PTIC).

In an attempt to reduce the high relapse rate associated with ABMT, five children with high-risk first CR and 19 in second or subsequent CR lacking matched family allogeneic donors underwent ABMT with chemopurged bone marrow utilizing verapamil (VPL), vincristine, and VP-16. Patients were conditioned with TBI, VPL bolus and infusion with VP-16 and cyclophosphamide. The first cohort of patients (n = 4) received only cyclosporin A (CsA). The second cohort (n = 7) received CsA and alpha interferon (total = 11 with post-transplant immunotherapy alone.) The third cohort (n = 13) received CsA and six alternating cycles of alphaIFN and chemotherapy and six additional cycles of chemotherapy (vincristine, VP-16, Ara-C, prednisone) followed by G-CSF (post-transplant immune chemotherapy (PTIC)). The 2-year DFS is 42+/-10% (90% confidence interval (CI) is 26.5-58.5%) and 2-year overall survival is 54+/-10% (90% CI is 37.5-70.5%). Furthermore, patients receiving PTIC (n = 13) vs immunotherapy alone (CsA+/-aIFN) (n = 11) had a substantially better 2 year DFS and OS: 69+/-13% vs 13+/-12% and 85+/-10% vs 25+/-15% (P = 0.008 and P = 0.06, respectively). These results suggest that the use of ABMT with chemopurging, combined with PTIC is well tolerated and may be an alternative new approach in the treatment of a subset of children with high-risk first CR or > or = second CR ALL who lack closely matched family-related allogeneic donors.

Adolescent↗