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Biomedical subjects

R C Rees

Publications and source records attributed to R C Rees.

At least 127 records · Page 7Linked to original sources
PubMed1987

Metastatic heterogeneity in a spontaneously metastatic HSV-2 induced hamster fibrosarcoma: association of phenotypic and genotypic properties with metastatic potential.

A spontaneously metastatic tumour of hamsters and cell lines derived from its in vivo metastatic deposits, or from in vitro cloning were compared for immunobiological and genotypic variation and correlation sought with regard to metastatic potential. Cell lines were established from seven individual lung metastases following primary tumour resection of the parent (HSV-2-333-2-26) cell line. When inoculated subcutaneously, and upon resection of the subsequent tumour mass, four cell lines (MetA, MetB, MetE and MetF) demonstrated greater, one similar (MetG) and two (MetC and MetD) less metastatic capacity compared with the parent tumour line. In further studies cell lines were established in vitro by single cell cloning of the parent tumour either by limiting dilution or soft agar cloning. In vivo tumour resection experiments showed eight cell lines (S4, S7, S4A, S7A, S7B, C1.1, C1.4 and C1.5) to have an increased metastatic potential and five cell lines (S8, S9, S8B, S9D and S9E) a decreased metastatic potential compared to the parental line. Karyotypic analysis of the cells revealed that all highly metastatic cell lines were of a near diploid genotype, whilst non- and weakly metastatic cell lines, including the parental line, were aneuploid or near tetraploid. The immunobiological characteristics of these cell lines was studied. Assessment of in vivo immunogenicity showed that eight clones (MetA, MetB, MetE, MetF, S7A, C1.1, C1.4 and C1.5) were non-immunogenic whilst the parental tumour line and three clones (MetC, MetD and MetG) exhibited a strong transplantation rejection antigen; immunogenicity showed an inverse correlation with metastatic potential. Susceptibility to NK cytolysis was demonstrated for cell lines exhibiting a weak or non-metastatic/immunogenic phenotype. The origin of metastatic variants and their association with genotype and immunobiological properties is discussed.

Animals↗
PubMed1987

Augmentation of human natural killer cell activity by influenza virus antigens produced in Escherichia coli.

A series of Escherichia coli cloned influenza viral gene products were assayed for their ability to augment human natural cytotoxicity in overnight cultures (18 h) at 37 degrees C. Nylon wool nonadherent peripheral blood mononuclear cells (PBMC) proved responsive to stimulation by a number of cloned viral proteins, the most effective being the nonstructural (NS1) protein (but not NS2 protein) and haemagglutinin and matrix antigen components fused to the N-terminal 81 amino acid sequence of NS1. Furthermore, interferon (IFN) was generated in cultures in which enhanced cytotoxicity was detected and was identified as mostly IFN alpha (greater than 90%) with less than 10% IFN gamma contamination. The cell type responding to antigen stimulation was present in Percoll fractions enriched for large granular lymphocytes (LGLs); furthermore PBMC activated by NS1 protein fractionated in the low density Percoll fractions (LGL enriched). Using specific anti-IFN antisera, it was shown that IFN alpha but not IFN gamma was responsible for the enhancement of cytotoxicity. Interferon induction and activation of cytotoxicity could not be ascribed to the presence of contaminating bacterial products. These results suggest that a particular NS1 protein configuration is capable of activating human natural killer cells via the induction of IFN alpha.

Antigens, Viral↗
PubMed1986

Production of plasminogen activator by a primary HSV-2-induced hamster fibrosarcoma and its in vivo derived sublines.

The plasminogen activator (PA) content of a primary HSV-2-induced hamster fibrosarcoma and sublines derived from its in vivo metastases was investigated using the indirect 125I-labeled fibrin plate method. Fresh tissue culture lines established from primary HSV-2-333-2-26 tumors were shown to produce levels of PA similar to sublines derived from lung or kidney foci that developed after resection of primary tumors. In comparison, normal hamster embryo fibroblast (NHEF) and baby hamster kidney cells produced little or no PA, although baby hamster lung fibroblasts produced intermediate levels of PA. In addition, no correlation was found between PA levels of the sublines and their ability to metastasize from subcutaneous tumors, although tumor cell lines were shown to produce significantly more PA than normal cells.

Animals↗
PubMed1986

Suppression of natural and activated human antitumour cytotoxicity by human seminal plasma.

The influence of human seminal plasma (SP) and whole semen (S) on the expression of natural cytotoxicity by human peripheral blood mononuclear cells (PBMNC) was examined. Marked suppression of natural cytotoxicity against K562 targets was observed when effectors were pre-treated for 1 h with SP or S diluted up to 1:400. Abrogation of cytolytic activity by SP was not the result of direct lymphotoxicity, although a reduction of approximately 50% in the number of target binding cells was observed. In addition, the cytotoxicity of interferon (alpha-IFN, beta-IFN, gamma-IFN) and interleukin 2 (IL-2) activated human PBMNC was suppressed by components present in human SP, although IL-2 activated human PBMC were relatively resistant to suppression compared with other effector (spontaneous or activated) populations. Following 1 h exposure to SP, PBMNC failed to recover more than 25% of their initial cytotoxic potential upon further in vitro incubation (18 h) in the absence of SP. However, both interferon and IL-2 caused an increase in the cytotoxicity of these populations, in some instances to the level obtained with control, IFN or IL-2 activated PBMNC. The biological significance of SP as an inhibitor of immune function under experimentally defined conditions is discussed in relation to its possible role in vivo.

Cytotoxicity, Immunologic↗
PubMed1986

Seminal plasma suppression of human lymphocyte responses in vitro requires the presence of bovine serum factors.

The effect of bovine sera on the ability of human seminal plasma (SP) to suppress lymphocyte responses was investigated. Marked suppression of natural cell-mediated cytotoxicity (NCMC) against K562 targets was observed when effectors were pretreated for 1 h with SP (1:50 dilution) in the presence of 10% newborn calf serum (NBCS). Some suppression of natural cytotoxicity was observed when the effectors were treated with SP in the presence of 10% fetal calf serum (FCS) and this suppression was greater if the length of pretreatment with SP was increased to 20 h. Suppression of NCMC did not occur, or was considerably less, when the effectors were treated with SP in the presence of 10% autologous human plasma or in HB103 serum-free medium. The effect of bovine sera on suppression of T lymphocyte response to mitogen was also examined. Pre-treatment of lymphocytes with SP (1:50 dilution) for 1 h in the presence of 10% NBCS was sufficient to abrogate completely the stimulatory effect of PHA. In the presence of 10% FCS it was necessary for SP to be present throughout the assay for suppression to occur. In HB103 medium, stimulation was only slightly decreased below control values when SP was present throughout the assay, but suppression was considerably less than that obtained upon addition of NBCS or FCS to the culture medium. These findings imply that suppression of lymphocyte activity by SP is dependent on the presence of exogenous serum co-factors and in the light of this finding, the clinical relevance of SP suppression may require re-examination.

Animals↗
PubMed1985

The calmodulin content of normal and leukaemic lymphocytes.

Normal human peripheral blood mononuclear cells (PBMC) and leukaemic cell lines (three of human and one of gibbon origin) were found to contain similar levels of calmodulin (CaM) when expressed relative to the total cell protein. Two of the cell lines examined further were found to contain much higher amounts of CaM per cell (up to 5-fold) than PBMC but this was readily explained by their much greater cell size. Variations in CaM levels were noted during culture of both PBMC and leukaemic cells which were apparently independent of the percentage of cells undergoing active division in these cultures. These results do not support the contention that transformed cells contain a higher proportion of CaM than normal cells.

Calmodulin↗
PubMed1985

The roles of two peritoneal T-lymphocyte populations in the in vivo rejection of methylcolanthrene-induced sarcoma.

Two phenotypically distinct T-lymphocyte populations infiltrating the peritoneal site of active tumor rejection were found to have specific reactivity against methylcolanthrene (MCA)-induced sarcoma(s) in two separate biological assays. One, expressing a Lyt 1+2- phenotype, mediates specific delayed type hypersensitivity (DTH) reaction to the immunizing MCA tumor transplantation antigen, and the other, expressing a Lyt 1+2+ phenotype, transfers in vivo protection against the MCA tumor in Winn assay. This latter antitumor immunity was specific for individually distinct transplantation antigens of each MCA sarcoma line. In contrast, standard transplantation tests by direct (whole animal) challenge demonstrated considerable tumor cross-reactivity. These findings and the relative contributions of the two T-cell populations are discussed in terms of effector mechanism.

Animals↗
PubMed1985

An assessment of natural cell-mediated cytotoxicity in patients with malignant lymphoma.

Fifty per cent of untreated malignant lymphoma patients were shown to have profoundly reduced levels of peripheral blood lymphocyte-natural cell mediated cytotoxicity (PBL-NCMC) when tested against the leukaemic cell-line K562; assessment of NCMC in unfractionated blood from a large number of these patients showed a comparable reduction in activity. High levels of NCMC were observed in some patients with stage III/IV non-Hodgkin's lymphoma (NHL), while Hodgkin's disease (HD) patients over 40 yr of age had normal levels. In both NHL and HD patients there was no correlation between NCMC and absolute lymphocyte count or lymphoma histology. Human interferon was seen to boost NCMC in the majority of NHL patients, but most HD patients were nonresponders. Almost all patients tested had normal number of target binding lymphocytes, and most had numbers of HNK-1+ cells within the control range. However, on exposure to IFN, the number of target binding lymphocytes increased in over half of the patients tested, with some patients showing an increase in HNK-1+ cells, in the majority of cases without enhancement of NCMC.

Adult↗
PubMed1984

Non-random chromosome changes in a herpes-virus-transformed Syrian hamster cell line and its metastatic derivatives.

A primary subcutaneous tumour of low spontaneous metastatic capacity, produced after inoculation of Herpes-virus hominis type-2-transformed hamster fibroblasts (parent line) and two in vivo derived highly metastatic lung deposits (Met A and Met B) were karyotyped and compared after trypsin G-banding. The parent line was cytogenetically heterogeneous with a modal chromosome number of 74. However, a number of cells were of a higher ploidy level. A large variation in both numerical and structural abnormalities was observed, the chromosome rearrangements were often complex and unstable, but all the cells contained a theme of common marker chromosomes. Met A and Met B were near diploid (mean chromosome numbers 42 and 44 respectively) with a low level of tetraploid cells. They shared many chromosome rearrangements but could be readily distinguished by an additional translocation unique to Met A. Cytogenetic homogeneity within and between metastases suggested that they were of monoclonal origin and had been derived from a karyotypically similar subpopulation within the parent tumour. We were unable to detect such cells in the parent line; thus, their numbers within the parent tumour were likely to be low. Metastasis, therefore, has been highly selective, depending on the particular phenotypic properties of Met A and Met B. All cells of the parent and metastatic lines have homogeneously staining regions (HSR) and abnormalities of chromosomes 15 (C15) which may be important in tumorigenesis. In addition, Met A and Met B cells have a number of chromosome rearrangements [translocations, deletions and a double minute chromosome (DM)] not present in the parent cells. They are retained at a high frequency in the cells of Met A and Met B and thus it seems likely that the metastatic phenotype is associated with one or more of these chromosome aberrations.

Animals↗
PubMed1984

Properties of a herpesvirus-transformed hamster cell line: immunogenicity of sublines of high and low metastatic potential.

The immunogenicity of a herpesvirus hominis type-2-transformed hamster cell line (HSV-2-333-2-26) of low spontaneous metastatic ability was compared with that of its two in vivo-derived sublines of increased metastatic potential. The parent (HSV-2-333-2-26) tumour was immunogenic as assessed by protection against tumour challenge afforded by implantation of irradiated tumour cells or tissue. In contrast, the two metastatic sublines, designated Met A and Met B, were non-immunogenic as defined by the above critera . However, the parent Met A and Met B tumours were shown to possess a common antigen(s), since immunization with irradiated parent tumour cells afforded protection to challenge with Met A or Met B. Immunization with the metastatic sublines, however, gave no protection to homologous or heterologous tumour challenge. Bacillus Calmette-Guérin (BCG) inoculated in admixture with irradiated tumour cells and followed 7 days later by one immunization with X-irradiated tumour cells alone, increased host immunocompetence to subsequent homologous or cross-tumour cell challenge with parent, Met A or Met B cells. The immunity raised by using BCG plus irradiated tumour cells was shown to be specific to antigens expressed on the HSV-2 parent cell line and its metastatic sublines. In addition, BCG admixed with live inocula of parent, Met A or Met B cells induced contact suppression of in vivo tumour growth of the parent cells, but not of Met A or Met B cells. It is suggested from these studies that the parent tumour possesses a tumour-specific transplantation antigen(s) ( TSTAs ) which is not functionally active on its metastatically derived sublines. Common antigens, shared between the parent and Met A and Met B cells, are detectable by cross-challenge experiments, but they themselves appear not to be immunologically offensive. The loss of immunogenicity is discussed as a possible mechanism for the in vivo selection of sublines with increased metastatic potential.

Animals↗
PubMed1984

Enhancement of tumor growth in mice: evidence for the involvement of host macrophages.

Intratumor host cells of methylcholanthrene-induced fibrosarcoma(s) were shown to enhance the in vivo outgrowth of syngeneic homologous tumors (MC1A, Mc2A, Mc2B) but not two heterologous T-lymphomas (EL4 and TLX9) in the Winn adoptive transfer assay. This enhancing activity was not restricted only to the latent period of tumor growth but was also observed during the period of active in vivo tumor proliferation. Tumor enhancement was mediated by a population of cells adherent to nylon wool and glass and insensitive to irradiation (with 850 rads) or to treatment with anti-Thy 1.2 serum and complement. Macrophages from peritoneal exudates of normal mice, used as control host cell population, showed similar tumor-enhancing activity. These findings suggest that tumor infiltrating host cells, predominantly macrophages appear to be the cell type responsible for tumor enhancement and active promotion of tumor growth (in vivo).

Animals↗
PubMed1984

The nature of enhanced natural killer lymphocyte cytotoxicity during anesthesia and surgery in patients with benign disease and cancer.

This study was instituted to determine the mechanism of enhanced natural killer (NK) lymphocyte activity during surgery. Natural cytotoxicity of whole blood to K562 target cells was assayed before anesthesia and during anesthesia and surgery in patients with benign and malignant gastrointestinal disease. Those patients with benign conditions and localized primary tumors showed enhanced NK lymphocyte cytotoxicity during surgery (p less than 0.025 and p less than 0.0025, respectively) but not patients with disseminated tumors. In patients with localized tumors, enhancement of NK lymphocyte cytotoxicity was an interferon-independent phenomenon but appeared to be related to a significant rise in the percentage of cells bearing the Leu 7 monoclonal antibody marker for NK cells (p less than 0.02). Exogenous leukocyte interferon caused further enhancement of NK cytotoxicity in patients with benign disease and some cancer patients. Enhancement of NK lymphocyte activity during surgery may be of significance in reducing tumor metastases by stimulation of natural cytotoxic mechanisms to circulating tumor emboli.

Adenocarcinoma↗
PubMed1984

Modulation of human natural killer cytotoxicity by influenza virus and its subunit protein.

The influence of intact influenza virus and purified detergent solubilized haemagglutinin (HA) subunits from these viruses on human natural killer (NK) cell activity was examined. Effector cells incubated with whole influenza virus for 18 hr initiated the production of alpha interferon which was associated with the enhancement of NK cell activity. In contrast, purified influenza virus HA suppressed NK activity in a dose-dependent manner, when added at the onset of the cytotoxicity assay, or when used to pre-treated effector cells prior to assay for cytotoxicity against K562 target cells. Effector cells exposed to influenza HA for 90 min, washed and re-incubated in fresh medium for up to 18 hr, failed to regain their cytotoxicity. Suppression of NK cell cytotoxicity could not be ascribed to direct toxicity of HA preparations or residual detergent and preservative in these preparations. The augmented cytotoxicity of activated human effector cells was also susceptible to suppression by virus HA, and pretreatment of human PBL effector cells with HA for 90 min, prior to exposure to human alpha interferon caused NK effector cells to become refractive to the enhancing effects of HIFN. That direct interaction between influenza virus HA and effector cells was a requirement for suppression of activity was shown in experiments using Bromelain-released influenza HA, which would not be expected to bind to cells and which failed to suppress NK cell activity.

Bromelains↗
PubMed1983

A modified short-term cytotoxicity test: assessment of natural cell-mediated cytotoxicity in whole blood.

Using whole blood from normal subjects, we have observed natural killing of K562 cells in a 4 h 51Cr-release assay comparable with that shown by separated PBMC and whole blood depleted of serum components. Separated plasma was not toxic towards K562 targets, and failed to potentiate the level of PBMC cytotoxicity through ADCC. The presence of red blood cells did not influence natural killing. The natural cytotoxicity of whole blood was augmented by interferon and depressed by prostaglandins E1 and E2. Studies with appropriate control blood fractions show that cytotoxicity tests with whole blood provide results reflecting natural cell-mediated cytotoxicity.

Alprostadil↗
PubMed1983

Detection and characterization of natural killer cells in Syrian golden hamsters.

Natural killer (NK) cell activity was observed in the peripheral blood and spleen of 8- to 10-week-old Syrian golden hamsters, but not in the bone marrow or thymus. Low, but significant, levels of cytotoxicity were also observed in mesenteric and axillary lymph nodes and cells harvested from the peritoneum. Cytotoxicity, in a 4-hr 51Cr-release assay, was found to be nylon wool non-adherent and was significantly reduced by treatment with trypsin or incubation at 37 degrees C for 18 hr. Natural cytotoxicity was shown to be low at 1 week of age, but increased to a maximum at 8 weeks and was maintained into old age. Correlation was observed between peripheral blood cytotoxicity and the presence of large, often granular, lymphocytes following fractionation of effector cells by Percoll discontinuous gradient separation. These findings are compared with previous studies in hamsters, where the results of longer-term cytotoxicity tests differ in some respects to those of the present study.

Aging↗
PubMed1983

Susceptibility of human ocular melanoma cells to spontaneous and interferon-augmented natural cytotoxicity.

Due to the current interest in natural killer (NK) cells as a host defence mechanism against neoplasia, we have investigated the susceptibility of short-term cultures of human ocular melanoma cells to spontaneous and interferon (IFN)-augmented natural cytotoxicity. Cultures of ocular melanoma cells were readily established and identified as bipolar and multipolar pigmented melanoma cells. In short-term cytotoxicity assays these cell lines demonstrated a weak susceptibility to spontaneous human PBL natural cytotoxicity, and increased killing was observed using IFN-augmented cytotoxic effector cells. These findings may be pertinent in relation to the role of NK cells in vivo.

Cells, Cultured↗
PubMed1983

Reduced susceptibility to natural killer cell lysis of hamster tumours exhibiting high levels of spontaneous metastasis.

The natural killer (NK) cell susceptibility of hamster tumours exhibiting high and low levels of spontaneous metastasis in vivo was investigated. The parent cell line (HSV-2-333-2-26), which was weakly metastatic, and the NK-sensitive target line K562 were both sensitive to hamster natural killer cell activity. In contrast, 2 in vivo cloned sublines, designated met A and met B, exhibited a high level of spontaneous metastasis and were shown to be weakly or non-susceptible to hamster UK reactivity.

Animals↗