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Biomedical subjects

A D Ho

Publications and source records attributed to A D Ho.

At least 127 records · Page 7Linked to original sources
PubMed1996

Three distinct domains in the HOX-11 homeobox oncoprotein are required for optimal transactivation.

HOX-11 (tcl-3) is a homeobox oncogene isolated from the breakpoint region of the t(10;14) chromosomal translocation recurring in T-cell acute lymphoblastic leukemia. Here we demonstrate that the HOX-11 homeoprotein mediates transactivation of reporter genes through various promoters in both mammalian and yeast cells. By deletion analysis, the transactivation domains of HOX-11 have been mapped to three amino acid stretches in the homeoprotein, the glycine-proline-rich region at the amino terminus, the homeodomain and the glutamine-rich region at the carboxyl terminus. The three distinct functional domains of HOX-11 act in concert for optimal transactivation. In addition, the homeodomain of HOX-11 appears to be differentially utilized in a promoter-dependent manner. Our data support the notion that the HOX-11 homeoprotein functions as an oncogenic transcription activator in leukemogenesis.

3T3 Cells↗
PubMed1996

Subcutaneous T-cell lymphoma with associated hemophagocytic syndrome and terminal leukemic transformation.

We report a case of subcutaneous T-cell lymphoma that presented as recurrent subcutaneous nodules, pancytopenia, and fever. Histopathologic examination revealed a dense infiltrate of markedly atypical lymphoid cells localized to the panniculus. These cells were identified as T cells by immunohistochemistry. There was associated karyorrhexis and fat necrosis. Hemophagocytosis was present both in the panniculus and in the bone marrow, with no tumor evident outside the subcutaneous tissue. Despite chemotherapy in conjunction with an autologous bone marrow transplant, the patient died after metastases, including explosive leukemic transformation, developed. Review of the literature shows subcutaneous T-cell lymphoma to be a rare peripheral T-cell lymphoma, often mistaken initially as a benign panniculitis, that manifests an aggressive, fulminant presentation in approximately one half of the patients; the remainder transform into a high-grade malignancy after months to years. The hemophagocytic syndrome, though to be a reactive T-cell process mediated by cytokines, is a frequent complication of this lymphoma and is responsible for its poor prognosis. Our patient uniquely demonstrated fatal leukemic transformation.

Adult↗
PubMed1996

The selective uptake of benzoporphyrin derivative mono-acid ring A results in differential cell kill of multiple myeloma cells in vitro.

High-dose chemotherapy (HDCT) and autologous bone marrow/blood stem cell transplantation are an effective combination for treating a number of malignant disorders. The contamination of the autograft by malignant cells may be a reason for recurrences in spite of this treatment, for instance, in multiple myeloma. Therefore, we evaluated the use of photodynamic therapy (PDT) using the photosensitizer benzoporphyrin derivative mono-acid ring A (BPD-MA) on multiple myeloma cells in comparison to the components of the normal bone marrow (NBM) and peripheral blood apheresis product. Flow cytometry was used to measure differential BPDMA uptake of NBM components: namely lymphocytes, monocytes, granulocytes and enriched hematopoietic stem cell (CD34+) populations and also the multiple myeloma cell lines OCI-MY7 and OCI-MY4. When each population was measured individually, the order of uptake was [OCI-MY7/MY4] > [CD34+] > [granulocytes] = [monocytes] >> [lymphocytes]. Further, clonogenic assay was used to demonstrate surviving fractions for OCI-MY7, OCI-MY4 and NBM in vitro. The LD90 for OCI-MY7 and OCI-MY4 was between 10 and 20 ng/mL BPD-MA whereas this concentration did not show any significant cell kill for the colony-forming units-granulocyte/macrophage (CFU-GM) and burst-forming units-erythrocyte (BFU-E). When the NBM was "contaminated" with multiple myeloma cells in vitro, the LD90 for OCI-MY7 in this cell mixture was shifted to between 40 and 80 ng/mL BPD-MA. However, at 40 ng/mL BPD-MA at least 50% of normal CFU-GM and BFU-E colonies survived. For CFU-GM and BFU-E derived from the enriched CD34+ cell population, BPDMA up to a concentration of 80 ng/mL did not significantly reduce the surviving fractions. We have observed a 3-4 log therapeutic window with differential cell kill when comparing multiple myeloma cell lines to the components of the NBM and apheresis product in vitro. We conclude, that BPD-MA is a molecule potentially useful as an ex vivo purging agent.

Bone Marrow↗
PubMed1996

Cell-cycle kinetics and VSV-G pseudotyped retrovirus-mediated gene transfer in blood-derived CD34+ cells.

As hematopoietic stem and progenitor cells have a low mitotic index, we have quantitated the impact of cytokine combinations on cell cycling of CD34+ cells and, using VSV-G pseudotyped retroviral vectors, correlated our findings with ex vivo gene transfer. We tested nine different combinations of cytokines for induction of human peripheral blood CD34+ cells into cell cycle over 72 hours. Using the 5-bromodeoxyuridine-Hoechst 33258 (BrdU-Hoechst) assay, we measured the cell-cycle kinetics. The combinations of cytokines tested that were most efficient in inducing the CD34+ cells into cycle were stem cell factor (SCF) plus one of the following: interleukin-1 (IL-1), IL-3, granulocyte colony-stimulating factor (G-CSF). The maximum numbers of cells in S+G2M phase were observed after 48 hours of culture. At least 35 +/- 5% of the CD34+ cells remained quiescent in the first G0/G1 phase, however, no matter which cytokine combination was used. Cell-cycle analysis of the CD34+CD38- subset by 7-amino actinomycin D staining did not detect cycling cells during 72 hours of culture with any of the cytokines tested. To investigate whether the cells could be infected by the VSV-G pseudotyped virus containing the neomycin phospho-transferase gene (neo), we exposed CD34+ cells to the virus for 7-8 hours after 0, 36, and 48 hours of cytokine stimulation. Total CD34+ cells and the CD34+CD38- subset were analyzed by polymerase chain reaction (PCR) for reverse-transcribed viral DNA of the neomycin resistance gene (RT-neoDNA). Immediately after exposure to the virus, RT-neoDNA was detectable in CD34+ cells that have been cultured with or without cytokines for 36 to 48 hours. Forty-eight hours postinfection, however, RT-neoDNA could be detected only with cytokine combinations that induced mitosis of the CD34+ cells, consistent with the requirement for mitotic activity for retroviral integration. Similar experiments performed with the 34+CD38- subset showed that RT-reoDNA could not be detected at any time point. Thus, postinfection RT-neoDNA could be immediately detected in noncycling CD34+ cells but not in CD34+CD38- cells. These results suggest during short-term liquid culture, there may be blocks for reverse transcription of retroviral RNA in CD34+CD38-cells in addition to the lack of mitotic activity.

ADP-ribosyl Cyclase↗
PubMed1996

Pluripotent and lineage-committed CD34+ subsets in leukapheresis products mobilized by G-CSF, GM-CSF vs. a combination of both.

To define an optimal regimen for mobilizing blood-derived progenitor cells from healthy donors for allogeneic transplantation, we have studied the early and lineage-committed CD34+ subsets in the leukapheresis products after mobilization with G-CSF (10 micrograms/kg/d), GM-CSF (10 micrograms/kg/d), and the combination of G-CSF and GM-CSF (G/GM, 5 micrograms/kg/d of each). We used three color and five dimensional flow cytometry with a panel of monoclonal antibodies against CD3, CD7, CD10, CD11b, CD15, CD33, CD34, CD38, CD45, CD61, and CD71. As reference, we also analyzed CD34+ subsets in samples from umbilical cord blood (UCB) and from adult bone marrow (BM). The level of total CD34+ cells was 0.04 +/- 0.03% (mean +/- SD) in peripheral blood at baseline, and reached a maximum on day 5 or day 6 of administration of growth factors. The percentages of CD34+ cells in the leukapheresis products were 1.06 +/- 0.37% (mean +/- SD) with G-CSF mobilization, 0.35 +/- 0.24% with GM-CSF, and 0.92 +/- 0.61% with the combination of both. Among the CD34+ subsets, the percentage of cells that were CD34+/CD38- was highest in UCB (7.18 +/- 5.58%) and lowest in G-CSF mobilized peripheral blood (0.80 +/- 0.22%), whereas GM-CSF or G/GM mobilized products gave rise to intermediate levels (4.43 +/- 3.40%, 3.61 +/- 2.42%, respectively). The differences between G/GM and G-CSF, between UCB and G-CSF, or between UCB and BM are significant. The absolute numbers of CD34+/CD38- and CD34+/CD38-/HLA-DR+ subsets are also significantly higher in the G/GM mobilized products than in G-CSF products. The cloning efficiency of G/GM mobilized CD34+ cells was 2 times higher than that of G-CSF mobilized CD34+ cells, albeit the difference was statistically marginal. The profile of CD34+ subsets mobilized by the combination of G/GM approaches that found in UCB. Our data illustrate that different growth factors and regimens can preferentially mobilize different CD34+ subsets from normal donors, and that the combination of G-CSF and GM-CSF might be an optimal regimen.

Antigens, CD34↗
PubMed1995

Tyrosine phosphorylation is required for up-regulation of the HOX-11 (TCL-3) homeobox proto-oncogene in T cells.

HOX-11 (TCL-3) is a homeobox proto-oncogene isolated from the breakpoint region of the t(10;14) chromosomal translocation associated with pediatric T-cell acute leukemia. To better understand the transcriptional regulation of the HOX-11 gene in response to extracellular signals, the levels of HOX-11 RNA were examined in normal and leukemic human T cells upon phytohemagglutinin and hematopoietic growth factor stimulation. While individual hematopoietic growth factors tested did not show any effect on HOX-11 gene expression, a drastic increase in HOX-11 RNA was observed under the induction of phytohemagglutinin. In the presence of cycloheximide, a protein synthesis inhibitor, phytohemagglutinin-induced HOX-11 up-regulation was suppressed, indicating that HOX-11 acts as a delayed early response gene which requires protein synthesis. The HOX-11 gene expression was also suppressed by the tyrosine kinase inhibitors tryphostin and lavendustin A. Our data therefore suggest that the delayed early response of HOX-11 up-regulation in T cells requires a tyrosine phosphorylation signal.

Base Sequence↗
PubMed1995

Intracellular immunization of human fetal cord blood stem/progenitor cells with a ribozyme against human immunodeficiency virus type 1.

Successful treatment of human immunodeficiency virus infection may ultimately require targeting of hematopoietic stem cells. Here we used retroviral vectors carrying the ribozyme gene to transduce CD34+ cells from human fetal cord blood. Transduction and ribozyme expression had no apparent adverse effect on cell differentiation and/or proliferation. The macrophage-like cells, differentiated from the stem/progenitor cells in vitro, expressed the ribozyme gene and resisted infection by a macrophage tropic human immunodeficiency virus type 1. These results suggest the feasibility of stem cell gene therapy for human immunodeficiency virus-infected patients.

Antigens, CD↗
PubMed1995

Stem cells as vehicles for gene therapy: novel strategy for HIV infection.

Restoration of bone marrow and immune function by means of allogeneic bone marrow transplantation has been attempted in AIDS patients but has not been successful as the donor-derived cells, or their progeny, inevitably became infected. A hairpin ribozyme that specifically cleaves HIV-1 RNA has been developed by F. Wong-Staal et al. and has been demonstrated to confer resistance against HIV-1 infection. Allogeneic transplantation of CD34+ cells or their pluripotent subsets, transduced by vectors bearing this ribozyme gene, can protect the stem cells and their progeny from HIV-1 infection and eventually restores immune function. We have provided evidence that long-term repopulating stem cells can be mobilized into peripheral blood by growth factors. The combination of G-CSF and GM-CSF seems to yield a high frequency of pluripotent stem cells with a CD34+ subset profile that is similar to placental and umbilical cord blood (PUCB). We have then demonstrated a highly efficient transduction of CD34+ cells from PUCB and mobilized leukapheresis products by retroviral vectors bearing the ribozyme gene. Expression of the ribozyme gene, as shown by reverse transcriptase-polymerase chain reaction, was of similar magnitude (70%-90% of cells that grow into colonies). Challenge of the progeny macrophages from such transduced CD34+ cells with monocyte-trophic strains of HIV-1 showed that they were resistant to infection. Thus allogeneic transplantation of CD34+ cells or their pluripotent subsets, transduced with ribozyme gene, can be a promising strategy for the treatment of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Soluble CD4, soluble CD8, soluble CD25, lymphopoieitic recovery, and endogenous cytokines after high-dose chemotherapy and blood stem cell transplantation.

Mononuclear cell preparations from peripheral blood after mobilization with hematopoietic growth factors have been shown to induce accelerated neutrophil and platelet recovery as compared with that induced by autologous bone marrow transplantation after myeloablative chemotherapy. Because these mononuclear cell products contain many immunocompetent cells other than hematopoietic progenitors, these accessory cells might contribute to the rapid immunohematopoietic reconstitution. We have monitored the concentrations of soluble CD4 (sCD4), sCD8, and sCD25; the recovery of the lymphocyte subsets and of natural killer (NK) cells; and the endogenous levels of granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), IL-6, and granulocyte-macrophage-CSF (GM-CSF) in 12 patients who underwent high-dose chemotherapy supported by blood stem cells that were obtained by mobilization with chemotherapy and GM-CSF. The concentrations of both G-CSF and IL-6 peaked at 7 days after reinfusion of stem cells, and this transient elevation preceded the increase in the white blood cell count by approximately 5 to 7 days. The levels of sCD4 and sCD8 increased to a maximum on day 21, and the time to peak levels coincided with the maximum increase in white blood cell count, absolute neutrophil count, or lymphocytes. The levels of sCD25 were found to be elevated from day 7 to day 21. Statistically, the increases in sCD4, sCD8, sCD25, G-CSF, and IL-6 were highly significant, whereas there were no significant changes in IL-3 and GM-CSF. A rapid recovery of the NK activity was found in all 8 of the patients who could be monitored for this assay. Therefore, our study suggests that recovery of CD4+ cells, CD8+ cells, and NK activity coincided with that of neutrophils, which is preceded by a marked, but transient, elevation of IL-6 and G-CSF.

Adolescent↗
PubMed1994

Priming effects of granulocyte-macrophage colony-stimulating factor are coupled to cholera toxin-sensitive guanine nucleotide binding protein in human T lymphocytes.

In addition to the mobilization of neutrophils and monocytes, granulocyte-macrophage colony-stimulating factor (GM-CSF) also mobilizes lymphocytes into peripheral blood. We examined the ability of GM-CSF to induce the proliferation of purified human T cells (CD3+ CD4+ CD56- CD16- B1- MO2-) in two major aspects: (1) the mechanisms of GM-CSF interaction with interleukin-2 (IL-2) causing T-cell proliferation, and (2) the intracellular signals transmitted by GM-CSF in T lymphocytes. We observed that concentrations of GM-CSF between 0.01 ng/mL and 10 ng/mL had a synergistic effect with concentrations of IL-2 between 1 U/mL and 10 U/mL in stimulating T-cell proliferation. This effect of GM-CSF was maximal when it was added at the start of the culture. In situ hybridization showed the presence of mRNA for GM-CSF receptors in T cells. Further analysis showed that GM-CSF induced the expression of IL-2 receptor (IL-2R) on the surface of T lymphocytes. These events coincide with the ability of GM-CSF to increase the intracellular levels of both cyclic 3',5'-adenosine monophosphate (cAMP) and cyclic 3',5'-guanosine monophosphate (cGMP) in T cells, to increase the binding of (gamma-35S) GTP to T-cell membranes, and to enhance GTPase activity as determined by increased hydrolysis of 32P-GTP. IL-2 also induced IL-2R expression, cyclic nucleotide secretion, and G-protein activation. However, the presence of IL-2 reduced GM-CSF induction of these activities. Addition of antibodies to the alpha and beta subunits of IL-2R permitted the activation of G protein by GM-CSF even when IL-2 was present. Furthermore, GTP binding and GTPase activity induced by GM-CSF or IL-2 were inhibited by the addition of cholera toxin (CT), but not pertussis toxin (PT). Cumulatively, these results suggest that in T lymphocytes, receptors for GM-CSF or IL-2 may be coupled to the same CT-sensitive G protein, although other possibilities may exist. The role that G proteins play in mediating the intracellular signaling pathways induced by GM-CSF or IL-2 in human T cells is supported by adenosine diphosphate-ribosylation of a 44-kD or a 39-kD G protein in T-cell membranes by CT and PT, respectively.

Adenosine Diphosphate Ribose↗
PubMed1994

Multidrug resistance phenotype in patients with chronic lymphocytic leukemia as detected by immunofluorescence (FACS) and northern blot analysis.

The multidrug resistance (MDR) phenotype has been demonstrated to be related to the overexpression of P-glycoprotein, a 170 kDa transmembrane efflux pump. We studied P-glycoprotein expression in 40 patients with chronic B-cell leukemias by FACS analysis using MoAb c219, which recognizes both the MDR1 and the MDR3 gene product. We found significantly elevated P-glycoprotein expression in these patients as compared with normal controls. Patients who had received previous chemotherapy regimens containing MDR-related drugs showed significantly higher P-glycoprotein expression with MoAb c219 than those patients who had been untreated. Northern blot analysis of MDR1 and MDR3 gene expression in 32 of the patients gave a similar result: in the analysis of total RNA four of six patients (66%) pretreated with either vinca alkaloids or anthracyclines were MDR1 positive as opposed to 6 of 26 (23%) who had no treatment or treatment without these agents. In contrast, MDR3 expression was found more frequently (63%), but was randomly distributed in the differently treated groups. Increasing the sensitivity level by analysis of enriched mRNA (polyA+RNA) led to the detection of MDR1 and MDR3 expression all B-CLL patients. We conclude that a basic elevated P-glycoprotein expression is intrinsic in CLL cells, which is possibly upregulated under chemotherapy. This might be responsible for initial and acquired chemotherapy resistance in CLL patients. Follow-up of the B-CLL patients over 46 months showed that the median survival time for MDR1+ patients was 19 months as opposed to 46 months for MDR1- patients (p < 0.01). There was no statistical difference in survival between MDR3+ and MDR3- patients. In the MDR1+ group, eight of nine patients had developed resistance to the therapy with MDR-related drugs. The expression of MDR1 might, therefore, predict treatment failure with MDR-related drugs and be a negative prognostic factor.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

High efficiency retroviral-mediated gene transduction into CD34+ cells purified from peripheral blood of breast cancer patients primed with chemotherapy and granulocyte-macrophage colony-stimulating factor.

The hematopoietic system has been one of the major targets for designing human gene therapy protocols. In the present system, we have transduced LNL6, one of the most commonly used retroviral vectors in gene therapy, into purified CD34+ cells from peripheral blood of patients primed with chemotherapy and granulocyte-macrophage colony-stimulating factor (GM-CSF). Purification of CD34+ cells was achieved by incubation with a murine anti-CD34 monoclonal antibody (9C5), and subsequently with paramagnetic microspheres (Dynal) coated with sheep anti-mouse IgG1 (Fc). The CD34+ cells were released from the beads by treatment with chymopapain. Flow cytometry analysis using the anti-CD34 antibody HPCA-2-FITC targeted at another epitope of CD34 showed that 78-97.5% of the cells thus purified were CD34+. After retroviral-mediated gene transfer, polymerase chain reaction (PCR) analysis revealed that 67-100% of the hematopoietic colonies contained the marker gene neo, indicating that CD34+ cells purified by immunomagnetic microsphere method from peripheral mononuclear cells primed with hematopoietic growth factors are highly susceptible to retroviral-mediated gene transfer. The expression of neo as determined by reverse transcription (RT)-PCR appeared to be unstable and not persistent. Taken together, our data suggest that LNL6 is a suitable vector for gene marking of hematopoietic progenitors but not for gene therapy protocols based on persistent gene expression.

Antigens, CD↗
PubMed1994

Combination of mitoxantrone and etoposide in the treatment of myelodysplastic syndromes transformed into acute myeloid leukemia.

Mitoxantrone and etoposide have both been shown to be effective in de novo acute myeloid leukemia. Therefore, the combination of mitoxantrone and etoposide, the NOVE regimen, was examined in the treatment of myelodysplastic syndromes (MDS) transformed into acute myeloid leukemia (AML). Twenty-one previously untreated patients (eight females, thirteen males) with a median age of 56 years (range 28-67 years) were studied. Diagnosis of MDS was made within the range of six months to three years before transformation into AML occurred. The NOVE regimen consisted of mitoxantrone 10 mg/m2 day 1-5, and of etoposide 100 mg/m2 day 1-5. After one single course of therapy eleven patients achieved a complete remission (CR) and three patients a partial remission (PR). Nine patients (six in CR and three in PR) received a second course, and the PR was completed to a CR in one patient. Thus, the overall response rate was 66% (14/21 patients), and the CR rate was 57% (12/21 patients). Median duration of CR was 7 months (range 2-10 months). Median survival was 10 months (range 3-20 months) for complete responders and 3 months (range 1-10 months) for patients who did not achieve a CR. For patients with subsequent CR, median time of granulocytopenia (< 500/microliters) and thrombocytopenia (< 20.000/microliters) was 20 days and 18 days, respectively. In conclusion, the NOVE regimen appears to be effective in AML secondary to MDS. However, strategies for remission maintenance are warranted.

Adult↗
PubMed1994

The use of photodynamic therapy in bone marrow purging.

High-dose chemotherapy and autologous bone marrow transplantation are an effective combination for treating a number of malignant disorders. Clinical trials have demonstrated a potential role for this regimen in the management of acute leukemia and non-Hodgkin's lymphoma. Autologous bone marrow transplantation continues to be limited by high relapse rates, as compared with allogeneic bone marrow transplantation. Two factors are thought to account for this observation. First, autologous transplants lack the immunologic "graft-versus-host" advantage of allogeneic transplants. Second, autologous grafts have the possibility of tumor cell contamination. Methods to reduce tumor cell contamination in autografts include exposure to chemical agents or monoclonal antibodies; long-term marrow cultures; and immunologic manipulation, either with immunomagnetic devices or antibody/complement combinations. Photodynamic therapy (PDT) with porfimer sodium (Photofrin; manufactured by Lederle Parenterals, Carolina, Puerto Rico, under license from Quadra Logic Technologies, Inc, Vancouver, British Columbia, Canada) or benzoporphyrin derivative (BPD verteporfin; BPD-MA; BPD-Quadra Logic Technologies, Inc, Vancouver, British Columbia, Canada) may be an effective means of purging bone marrow. The ability of malignant cells to selectively accumulate photosensitizing agents may account for efficacy of PDT in bone marrow purging. The efficacy of porfimer sodium and BPD has been evaluated in cell lines known to express multidrug resistance (MDR), and the results compared with corresponding MDR-negative cell lines. Multidrug resistance-positive cell lines appear relatively resistant to BPD; porfimer sodium remains active. The reason for the differential effect of MDR positivity on the cytotoxicity of porfimer sodium and BPD is unclear, but is believed to be related to the larger size of the porfimer sodium molecule. Clinical trials evaluating PDT in bone marrow transplantation are under way.

Bone Marrow Purging↗
PubMed1993

Pentostatin in prolymphocytic leukemia: phase II trial of the European Organization for Research and Treatment of Cancer Leukemia Cooperative Study Group.

BACKGROUND: B-cell prolymphocytic leukemias or T-cell prolymphocytic leukemias are aggressive variants of chronic lymphoid leukemias. The small studies conducted to date have shown median survival durations of approximately 3 years for patients who have B-cell prolymphocytic leukemia and 7.5 months for those who have T-cell prolymphocytic leukemia, compared with about 8 years for patients who have chronic lymphocytic leukemia. In chronic lymphocytic leukemia, chemotherapy consisting of alkylating agents such as cyclophosphamide and chlorambucil combined with prednisone has achieved overall response rates of 50% to 70%, but this regimen has resulted in response rates of less than 25% in prolymphocytic leukemia. Pentostatin (2'-deoxycoformycin; DCF) is a purine analogue that has shown activity in treatment of chronic lymphoid malignancies. PURPOSE: This prospective phase II trial by the Leukemia Cooperative Group of the European Organization for Research and Treatment of Cancer was performed to assess the activity and toxicity of DCF in prolymphocytic leukemia. METHODS: Twenty patients with B-cell or T-cell prolymphocytic leukemia were given DCF at a dosage of 4 mg/m2 intravenously once a week for 3 weeks, then every other week for three doses. Patients who had at least partial response received maintenance therapy once a month for a maximum of 6 months. Fourteen patients had B-cell prolymphocytic leukemia, and six had T-cell prolymphocytic leukemia, as evidenced by morphologic and immunologic criteria; three were previously untreated, eight had been given one or two chemotherapeutic regimens, and nine had been given more than two. RESULTS: One patient died of an unknown cause during the first 6 weeks of treatment, and one died of disseminated toxoplasmosis during the period of maintenance therapy, 5 months after achieving partial remission. Nine (45% response rate) of the 20 patients achieved partial remission, including seven (50%) of 14 with B-cell prolymphocytic leukemia and two (33%) of six with T-cell prolymphocytic leukemia. The median duration of response was 9 months (range, 2-30 months); for patients with B-cell prolymphocytic leukemia, the median remission duration was 12 months. No complete remission was observed. Toxic effects included nausea and vomiting (30%), infections (30%), and transient increase in liver enzymes (35%) and in creatinine (20%) levels. Eight patients experienced thrombocytopenia, the major hematologic toxic effect; four had grade 3 or 4 toxic effects. CONCLUSION: DCF is active in prolymphocytic leukemia, even as salvage therapy in patients who had received multiple prior chemotherapeutic regimens. IMPLICATIONS: Trials using DCF or other purine analogues alone or in combination with standard chemotherapeutic agents in front-line or salvage therapy are warranted to improve the prognosis of patients with prolymphocytic leukemia.

Adult↗
PubMed1993

IL-8 induces the locomotion of human IL-2-activated natural killer cells. Involvement of a guanine nucleotide binding (Go) protein.

The effect of IL-8 on the in vitro locomotion of human IL-2-activated natural killer (IANK) cells was studied. It was observed that IL-8 induces chemokinesis in these cells, as determined by their migration in modified Boyden chambers. Bacterial toxins such as cholera toxin or pertussis toxin inhibited IL-8-induced chemokinetic activity, suggesting the involvement of guanine nucleotide-binding (G) proteins in IL-8 signal transduction in these cells. Pertussis toxin ADP-ribosylates a 39-kDa protein, whereas cholera toxin ADP-ribosylates a 43- to 45-kDa protein. Pretreatment of IANK cell membranes with 0.01 or 0.1 ng/ml of IL-8 and/or 5 microM GTP-gamma S did not affect pertussis toxin- or cholera toxin-dependent ADP-ribosylation. Western blot analysis showed that IANK cell membranes possess one Gi (39 kDa), two Gs (43 kDa and 45 kDa), and one Go (39 kDa). Pretreatment of IANK cell membranes with concentrations between 0.001 to 1.0 ng/ml of IL-8 resulted in the disappearance of the 39 kDa Go, but not Gi or Gs protein(s), suggesting that IL-8 receptors expressed on IANK cells are coupled to Go. Various concentrations of IL-8 enhanced the binding of GTP-gamma 35 S to IANK cell membranes, which further indicates the coupling of G proteins to IL-8 receptors in IANK cells.

Adenosine Diphosphate Ribose↗