Yoshitaka Kariya

Suppression by human placental protein 14 of natural killer cell activity

ABSTRACT: Human decidua of early pregnancy contains considerable numbers of CD3− CD56+ natural killer (NK) cells. In this study, two major protein products of the decidua, placental protein 14 (PP14) and placental protein 12 (PP12), were tested for the ability to regulate human NK cell activity. In vitro overnight exposure to PP14 of blood lymphocytes or purified large granular lymphocytes (LGL) resulted in suppression of cytotoxicity against K562 target cells in a 4‐h 51Cr release assay. The NK inhibition was dependent on concentrations of PP14, being detectable at 5 μg/ml and reaching maximum at 50 μg/ml. Manifestation of PP14‐induced NK suppression required 18‐h contact with NK cells. The suppression of NK activity by PP14 was not abolished by indomethacin. In a target binding assay the number of PP14‐treated LGL binding to K562 was comparable to that of untreated ones. By contrast with PP14, PP12 produced no effects on NK cells. These results indicate that PP14 suppresses the function of NK cells, which might be involved in prevention of maternal immune rejection of fetus at the fetomaternal interface.

Inhibition of proliferation and induction of apoptosis by abrogation of heat-shock protein (HSP) 70 expression in tumor cells

Tumor cells often express elevated levels of heat-shock protein (HSP) 70. The present study was designed to invesitgate the role of HSP70 in the proliferation and survival of tumor cells in the human system. When Molt-4 and other tumor cells were treated in vitro with HSP70 antisense oligomer, they displayed propidiumiodide-stained condensed nuclei (intact or fragmented). A ladder-like pattern of DNA fragments was observed with HSP70 antisense-oligomer-treated tumor cells in agrose gel electrophoresis, which was consistent with internucleosomal DNA fragmentation. Flow cytometry analysis revealed the hypodiploid DNA peak of propidium-iodide-stained nuclei in the antisense-oligomer-treated cells. The apoptosis induced by HSP antisense oligomer was dose- and time-dependent. The antisense oligomer induced apoptosis mainly in tumor cells at G1 and S phase, resulting in an inhibition of cell proliferation. HSP70 antisense oligomer caused DNA-sequence-specific inhibition of HSP70 expression, which preceded apparent apoptosis. These results indicate that HSP70 antisense treatment inhibits the expression of HSP70, which in turn inhibits cell proliferation and induces apoptosis in tumor cells and suggest that HSP70 is required for tumor cells to proliferate and survive under normal condition.

Accumulation of γ/δ T Cells in Human Dysgerminoma and Seminoma: Roles in Autologous Tumor Killing and Granuloma Formation

The precise biological function of a subset of T cells bearing gamma/delta T cell receptor (TCR) remains poorly understood. The present study demonstrated the presence of gamma/delta T cells in tumor-infiltrating lymphocytes (TIL) and peripheral blood lymphocytes (PBL) of human patients with dysgerminoma and seminoma when determined by flow cytometry and in situ immunohistochemical staining. TIL contained a high percentage of gamma/delta T cells, ranging from 17.3 to 35.1%. gamma/delta T cells often accumulated within the granulomatous inflammation of tumor tissues. The majority of gamma/delta T cells were V gamma 9/V delta 2+ cells. Freshly isolated PBL, TIL and purified gamma/delta T cells showed autologous tumor killing (ATK) activity, which could be inhibited by monoclonal antibodies (mAb) against V delta 2. Furthermore, two gamma/delta T cell clones established from TIL showed cytotoxicity against autologous and allogeneic dysgerminoma, while they had low or no lytic effects on other cell types including carcinomas of ovary and tumor cell lines such as K562, Daudi and Molt-4. Lysis of autologous tumor cells by the clone was inhibited completely by anti-V delta 2 mAb and partially by mAb against CD3, LFA-1 alpha and ICAM-1 molecules, while it was resistant to anti-CD8, anti-HLA-ABC and anti-HLA-DR mAb. Supernatants produced by gamma/delta T cell clones induced adhesion, aggregation and increased DNA synthesis of monocytes and some characteristics of activated macrophages or epithelioid cells. Tumor necrosis factor (TNF)-alpha, granulocyte-macrophage colony stimulating factor (GM-CSF) and interferon (IFN)-gamma were detected in the supernatants of gamma/delta T cell clone. These results suggest that gamma/delta T cells accumulating in dysgerminoma and seminoma exhibit ATK activity through V gamma 9/delta 2 TCR and these gamma/delta T cells also play a role in the formation of granulomatous inflammation, which is associated with human dysgerminoma and seminoma.

Activation of human natural killer cells by the protein-bound polysaccharide PSK independently of interferon and interleukin 2

The protein-bound polysaccharide PSK was tested for the ability to activate human natural killer (NK) cells. When blood lymphocytes and purified CD3-CD16+ large granular lymphocytes (LGL) were treated in vitro overnight with PSK, they demonstrated enhanced NK cell activity against K562. The PSK-activated killer cells also lysed NK-resistant targets and freshly isolated autologous and allogeneic tumor cells. The PSK effect was observed with concentrations that could be obtained in the blood of cancer patients receiving oral administration of PSK. PSK-induced enhancement of NK activity was not abrogated by monoclonal antibodies (mAb) that neutralized interferon (IFN) alpha, IFN gamma, or interleukin-2 (IL-2). In addition, mAb reactive with p55 (alpha chain) or p75 (beta chain) glycoproteins of IL-2 receptors had no effects on PSK-enhanced NK activity even when used simultaneously. These results indicate that the PSK could activate human NK cells independently of IFN and IL-2/IL-2R systems.

Suppression of natural killer cell activity by granulocytes in patients with aplastic anemia: role of granulocyte colony-stimulating factor

Patients with aplastic anemia were tested for natural killer (NK) activity, and the roles of granulocytes and granulocyte colony-stimulating factor (G-CSF) in the regulation of cytotoxicity were evaluated. Blood lymphocytes showed low or no NK activity against K562 targets. The depression of NK activity was more frequently recorded for patients who were not in remission and those who received G-CSF administration. Granulocytes of aplastic anemia patients with impaired NK activity suppressed the lytic activity of NK cells. By contrast, granulocytes from normal controls and aplastic anemia patients with normal NK activity had no suppressive activity. There was a good correlation between NK activity of lymphocytes and suppressive activity of granulocytes. Blocking of direct contact of suppressor and effector cells by cell chambers abolished suppression of cytotoxicity. NK suppression by granulocytes was resistant to treatment with catalase or superoxide dismutase. In vitro stimulation with G-CSF of granulocytes that naturally had no suppressive activity resulted in development of suppressive function, whereas granulocytes with natural suppressive activity were not further stimulated in vitro by G-CSF to express augmented activity. These results suggest that the presence of suppressor granulocytes in the blood could be one cause of the impaired NK activity in patients with aplastic anemia.

Studies on T-Lineage Cells in Human Decidua of First Trimester Pregnancies

ABSTRACT: T‐lineage cells in human decidua of early pregnancies were tested for surface markers, proliferative response, interleukin‐2 (IL‐2) production, and natural killer (NK) activity. T‐lineage (CD2+) cells that were obtained from decidua by the use of E‐rosette formation contained fewer CD3+ mature T cells and CD4+ cells than those from the peripheral blood of the same donors, while no differences were seen in the frequencies of CD8+ cells. P55 molecules of IL‐2 receptor (IL‐2R/p55, Tac antigen) were hardly detected on fresh decidual T‐lineage cells, though approximately 20% were positive for HLA‐DR. More than a half of decidual T‐lineage cells expressed CD56 molecules on their surface and killed K562 cells, the prototype target of NK cells, while most of them were negative for CD16 and CD57. Upon stimulation with IL‐2, decidual T‐lineage cells demonstrated dose‐dependent proliferative response. In addition, they were induced to produce high amounts of IL‐2 by stimulation with mitogens but not with alloantigens. These results suggest that human decidua contains high numbers of CD2+3‐CD16+56+ lymphocytes and that this population responds to IL‐2, produces IL‐2 and mediates NK activity.

Human Decidual Function in Trophoblast and Uterine Interaction

The decidua constitutes an anatomical compartment of the placenta in deciduate mammals including humans. By virtue of its anatomical location at the interface between maternal and fetal tissues, it has long been recognized that the decidua possesses a particular function which leads to the formation of an immunologically privileged site to accommodate the semi-allograft implant and its subsequent development.