Biomedical subjects

Ken Toba

Publications and source records attributed to Ken Toba.

30 records · Page 2Linked to original sources

PubMed2003

A comparative study of the JAM test and 51Cr-release assay to assess the cytotoxicity of dendritic cells on hematopoietic tumor cells.

Dendritic cells (DCs) are potent antigen presenting cells and possess a direct anti-tumor cytotoxic ability. Nevertheless, the mechanism of anti-tumor cytotoxicity by DCs and the methods for its evaluation are not fully elucidated. In order to clarify this mechanism of cytotoxicity, we examined the ability of DCs 1) to suppress [3H] thymidine (3H-TdR) uptake by tumor cells; 2) to induce cytolysis on 51Cr-labeled tumor cells; 3) and to induce DNA fragmentation on 3H-TdR labeled tumor cells (JAM test). Cytolysis and DNA fragmentation are markers of necrotic and apoptotic mechanisms of cytotoxicity in vitro, respectively. DCs inhibited approximately 38.6% to 54.8% of the growth of B4D6, NB4, U937, and Daudi cells as evaluated by the uptake of 3H-TdR. However no cytolysis was verified by 51Cr-release assay. On the other hand, cytotoxicity rates found using the JAM test ranged from 3 to 81% depending on the cell line and the effector to target cell ratio. The discrepancy of cytotoxicity between 51Cr-release assay and the JAM test may be due to the phagocytosis of apoptotic tumor cells or the absorption of released 51Cr by DCs surrounding the target cells. In conclusion, the JAM test was more sensitive than the 4-h and the 10-h 51Cr-release assay to investigate cytotoxicity mediated by DCs toward hematopoietic tumor cell lines in vitro.

Antigens, CD↗

PubMed2003

Cytoplasmic expression of EGFP in dendritic cells transfected with in vitro transcribed mRNA or cellular total RNA extracted from EGFP expressing leukemia cells.

The present study was designed for identifying the protein synthesis in cytoplasm of dendritic cells transfected with in vitro transcribed mRNA and cellular total RNA extracted from tumor cells. Dendritic cells were generated from cord blood-CD34+ cells by culture with GM-CSF, SCF, and TNF-alpha, or from peripheral blood adherent cells or CD14+ cells by culture with GM-CSF and IL-4. Dendritic cells were transfected with in vitro transcribed EGFP mRNA or cellular total RNA, which was isolated from EGFP expressing K562, by electroporation using a square-wave pulse. Optimal in vitro transcribed EGFP mRNA transfection efficiency (>90%) was observed in a single electroporation of 1.75 kV/cm (electric field strength) with a pulse width of 250 micros. Although the intensity of EGFP expression in dendritic cells transfected with cellular total RNA was less compared with that in dendritic cells transfected with in vitro transcribed EGFP mRNA, a definite cytoplasmic synthesis of EGFP was demonstrated in dendritic cells transfected with cellular total RNA. The visual identification of cytoplasmic expression of cellular total RNA in dendritic cells revealed that electroporation of tumor cell-derived RNA could be a useful tool to load dendritic cells with tumor antigens for establishing an efficient dendritic cell-based tumor immunotherapy.

Dendritic Cells↗

PubMed2003

Therapeutic role of pericardiocentesis for acute necrotizing eosinophilic myocarditis with cardiac tamponade.

We describe a patient with acute necrotizing eosinophilic myocarditis who recovered rapidly after pericardial drainage and without corticosteroid therapy. The 25-year- old man was referred to our hospital with suspected acute myocardial infarction on the basis of severe epigastralgia, abnormal Q waves and ST elevation on electrocardiography, and an increase in cardiac enzymes. Echocardiography disclosed pericardial effusion that compressed the right ventricle, left ventricular dysfunction in conjunction with posterolateral hypokinesis, and a thickened ventricular wall but no mural thrombus. The eosinophil count in the peripheral blood was slightly increased. Coronary angiography showed normal arteries and thus prompted an endomyocardial biopsy. The patient was transferred to the intensive care unit with a clinical diagnosis of myocarditis associated with cardiac tamponade. Emergency pericardiocentesis relieved symptoms immediately. The cells in the pericardial effusion were mainly eosinophils; interleukin 5 and interleukin 13 levels were predominantly elevated, and the effusion was drained for 5 days. The biopsy specimen revealed necrotizing eosinophilic myocarditis. Left ventricular function recovered within a week without corticosteroid therapy. No relapse was observed as of 8 months after diagnosis.

Adult↗

PubMed2002

Generation of functional and mature dendritic cells from cord blood and bone marrow CD34+ cells by two-step culture combined with calcium ionophore treatment.

The object of this study is to explore a culture method to generate a large number of functional and mature dendritic cells (DC) from human CD34+ hematopoietic progenitor cells. In the present study, we used a two-step method combined with calcium ionophore to induce DC from cord blood (CB) or normal human bone marrow (BM) CD34+ progenitor cells. The two-step method consists of 10 days of first step culture for the expansion and proliferation of CD34+ hematopoietic progenitor cells in the presence of SCF, IL-3, IL-6, G-CSF, and 7--11 days of second step culture for the induction of DC in the presence of GM-CSF, IL-4 and TNF-alpha. By the two-step culture, total nucleated cells were increased 208+/-66 (+/-SD, n=13), or 94+/-29 (n=5)-fold in the culture of CB or BM cells, respectively, compared with the number of CD34+ cells at the time of starting culture. Out of the total nucleated cells, 23 +/-10.4% of cells in CB cell culture and 25 +/-5% of cells in the BM cell culture acquired DC characteristic phenotypes, which were marked expressions of CD1a, HLA-DR, co-stimulatory molecules such as CD80, CD40, and adhesion molecule such as CD58. In allogeneic mixed leukocyte reaction (MLR), two-step cultured cells showed potent allo-stimulatory capacity. With this two-step culture, the absolute number of CD1a+ cells that co-expressed HLA-DR, CD80, CD40 and CD58 was enhanced approximately 3 times in CB cell culture and 1.9 times in BM cell culture, compared with the commonly used one-step culture method for the generation of DC from CD34+ cells using SCF, GM-CSF and TNF-alpha. However, on these DC generated in the two-step culture, the expressions of co-stimulatory molecule CD86 and mature DC marker CD83 were not sufficient. By the treatment of two-step cultured cells with calcium ionophore agent (A23187), the expression of co-stimulatory molecules such as CD86 and CD80 (especially CD86) was up-regulated. Besides, the expression of mature DC marker CD83 was remarkably induced by treatment with A23187 for a short duration (24 h). Consistent with the up-regulation of surface molecules CD86, CD80 and CD83, the two-step cultured cells treated with A23187 also showed a stronger allo-stimulatory capacity compared with the cells without A23187 treatment. In conclusion, the present study demonstrated that the two-step culture method effectively improved the yield of CD1a+ DC generated from CD34+ cells, and the phenotypes and functions of these CD1a+ DC could be enhanced efficiently by treatment with a calcium ionophore agent.

Antigens, CD34↗

PubMed2002

Acute promyelocytic leukemia developing in untreated essential thrombocythemia.

We describe a patient with untreated essential thrombocythemia (ET) who developed microgranular variant of acute promyelocytic leukemia, 9 years after the initial diagnosis of ET. He achieved complete remission (CR) but relapsed 11 months later. After achieving the second CR, he received peripheral stem cell transplantation from his HLA complete-matched sibling. Five months after the transplantation, he relapsed again with meningeal infiltration of leukemic cells. In this paper, we review cases of promyelocytic transformation of myeloproliferative diseases (MPD) other than chronic myeloid leukemia (CML). To our knowledge, this is the first case of promyelocytic transformation of Philadelphia chromosome negative untreated ET, in whom both t(15;17) and PML-RAR alpha fusion were proven.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2002

Acute T-lymphoblastic leukemia relapsed with the character of myeloid/natural killer cell precursor phenotype: a case report.

The leukemic lymphoblasts of a patient expressed CD7, CD13, CD33, CD34, HLA-DR and cytoplasmic CD3varepsilon. He was diagnosed with acute lymphoblastic leukemia (ALL), and successfully treated with a conventional chemotherapy for ALL. The disease relapsed three times, and the character of the cells gradually altered, i.e. CD56 expression increased and CD13, CD7 and cCD3 epsilon decreased. The phenotype of the relapsed ALL was, therefore, compatible with myeloid/natural killer cell precursor acute leukemia (M/NK-AL). Some of M/NK-AL may be closely related with T/myeloid-biphenotypic pro-T blasts, and both types of acute leukemia may develop a tendency to express myeloid antigens, and they may belong to the category of immature T lymphoid precursors.

Antigens, CD↗

PubMed2002

CD56+, NKp46+ cell line (MZ93) expressing T-cell and myeloid antigens.

The MZ93 cell line, established from a patient with CML, expressed CD4, CD7, CD13, CD25, CD33, CD34, CD56 and NKp46. The additional karyotype abnormality of the Ph-positive leukemia cells in vivo, 6p+, was also observed in MZ93. The early passages of MZ93 expressed CD3 in the cytoplasm, but the late passages did not. The cells did not express mature NK-markers as expected. The messenger RNAs of CD2 and NKp46 were detected and those of CD3varepsilon and CD3zeta were absent in the cells. Therefore, the cell line has the immunophenotype likely to NK and/or T cell precursor.

Antigens, CD↗

PubMed2002

Cutaneous lymphoblastic lymphoma of putative plasmacytoid dendritic cell-precursor origin: two cases.

Although the neoplasm of relatively mature type plasmacytoid dendritic cells (pDC) was recently reported, that of pDC-precursor has not yet been defined. We experienced two elderly male Japanese patients with reddish skin tumors. The histology of the tumors in both patients showed terminal deoxinucleotidyl transferase (TdT)-positive lymphoblastic lymphoma (LBL). The pathological cells did not express T, B or NK markers, and no rearranged bands were shown for immunoglobulin (Ig)-JH, T cell receptor (TCR)-C beta, J gamma, J delta1, and c-myc. In addition, no Epstein-Barr virus (EBV)-derived DNA was detected in either case. The cells were (CD45, CD43, CD74, CD10, and HLA-DR)-positive in both cases, and one of the cases showed (CD4, CD36, CD54, CD58 and CD86)-positive plasmacytoid lymphoblasts, which appeared to be compatible with intermediate cells between human bone marrow lymphoid precursors and mature lymphoid DC. The cutaneous LBL in the two cases may, therefore, have been of pDC-precursor origin.

Aged↗

PubMed2002

Difference in CD22 molecules in human B cells and basophils.

OBJECTIVE: CD22 is believed to be restricted to normal and neoplastic B cells. Human basophils were found to express CD22 molecules. Among the antibodies against CD22, Leu14, which recognized the ligand binding domain, reacted to basophils, and B3 and 4KB128, which recognized the amino terminus side and carboxy terminus side of the ligand binding epitope, respectively, did not. To clarify the difference of CD22 antigenicity in human B cells and basophils, we investigated RNA sequence and structures of CD22 molecules. MATERIALS AND METHODS: Purified B cells and basophils were obtained from normal human volunteers by using a MACS magnetic cell sorting system and anti-CD19 and anti-Fc epsilon R1 antibodies, respectively. RT-PCR and sequencing of CD22 mRNA were performed in the exons 3 to 8. Western blotting analysis of CD22 was also performed. RESULTS: The sequence of CD22 mRNA extracted from the basophils was the same as that of B cells in exons 3 to 8 (epitopes recognized by Leu14, B3, and 4KB128 were translated from exons 4 and 5). Reduced CD22 peptide extracted from the basophils reacted to Leu14 as well as B3 and 4KB128, and the molecular size of the reduced and nonreduced products was 130 kDa as expected. CONCLUSION: Disulfide bonds and the resulting 3D conformation of the CD22 molecules may have important roles in the difference of antigenicity of CD22 beta in B cells (CD22 beta 1) and basophils (CD22 beta 2). The difference in molecular structure surrounding the ligand-binding domain of CD22 may imply a specialization of the conformational forms of CD22 according to the ligand isoforms.

Adult↗

PubMed2002

Induction and characterization of cutaneous lymphocyte antigen on natural killer cells.

Cutaneous lymphocyte antigen (CLA) has been reported to be expressed mainly by memory/effector T lymphocytes infiltrating inflammatory skin lesions and cutaneous T-cell lymphoma. It has been suggested that CLA is a specific homing receptor, facilitating the T-cell migration into skin lesions, and also an indicator of the skin-homing T-cell subset. In the present study, we investigated the expression of CLA in natural killer (NK) cells defined phenotypically as surface CD3- and CD56+ cells in peripheral blood. CLA was definitely expressed on CD3-CD56+ cells at a level comparable to CD3+ cells in peripheral blood of normal Japanese volunteers. After in vitro stimulation of peripheral blood mononuclear cells with interleukin 2 (IL-2) and IL-12, there was a significant increase in the number and percentage of CLA+ NK cells but not CLA+ T cells (P < 0.01). To analyse the characteristics of CLA expressed by NK cells, we investigated a CLA+ NK-leukaemia cell line, NK-YS, established from a patient with NK leukaemia/lymphoma with skin infiltration. In the in vitro study, the CLA-expressing NK-leukaemic cell line bound to E-selectin-transfected cells and was inhibited by HECA 452 antibody or neuraminidase treatment of leukaemic cells. These findings suggest that CLA expressed by NK cells is a homing receptor for the E-selectin molecule and may explain skin infiltration by NK cells and NK lymphoma cells analogous to T cells. An NK-cell subset expressing CLA must play an important role in host defence against microorganisms and neoplasms in skin lesions.

Antigens, CD↗

PubMedDate not supplied

Expression of coxsackievirus and adenovirus receptor in neointima of the rat carotid artery.

Our previous study revealed that the coxsackievirus and adenovirus receptor (CAR) is a homophilic cell adhesion molecule and may function as a sensor of cell-cell interactions in the brain and damaged heart. In this study, we investigated if CAR expression is involved in the formation of neointimal hyperplasia using a balloon injury model of rat carotid artery. Cultured vascular smooth muscle cells (SMCs) from rat aorta were also studied. CAR antigen was constitutively detected in the endothelial cells (ECs) but not in SMCs before injury. On Day 5 after balloon injury, CAR was expressed strongly in the first layer of medial SMCs. Neointimal hyperplasia was observed on Day 7, and strong expressions of CAR concomitantly with proliferating cell nuclear antigen (PCNA) were obvious in the neointimal SMCs, while CAR in medial SMCs disappeared. The expression of CAR mRNA reached a peak on Day 7 and declined gradually to the basal levels. When the ECs regenerated on Day 14, CAR antigen was observed in the ECs but disappeared in the neointima. CAR together with PCNA was expressed abundantly in the proliferating SMCs in vitro and diminished in cells grown to a confluent state. The abundant expression of CAR in the neointima may facilitate an adenoviral gene therapy.

Animals↗

PubMedDate not supplied

Marked decrease of plasma VEGF after implantation of autologous bone marrow mononuclear cells in a patient with critical limb ischemia--a case report.

The authors performed autologous bone marrow mononuclear cells implantation (BMI) in a 79-year-old man with critical limb ischemia. After BMI, the resting pain of the ischemic leg improved gradually. They measured the plasma concentrations of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and serum hepatocyte growth factor (HGF) in the blood from bilateral femoral veins. Before BMI, the plasma VEGF and bFGF concentrations were much greater in the ischemic leg than in the other lower limb, but decreased to the same concentrations as those in the contralateral lower extremity after BMI. The large concentrations of the angiogenic factors VEGF and bFGF in plasma indicate the severity and extent of the leg ischemia. BMI resulted in lower levels of VEGF and bFGF, and this fall is the hallmark of the effectiveness of BMI in the treatment of peripheral artery disease.

Aged↗