Biomedical subjects

R C Rees

Publications and source records attributed to R C Rees.

At least 109 records · Page 6Linked to original sources

PubMed1990

The photokilling of bladder carcinoma cells in vitro by phenothiazine dyes.

The potential photodynamic therapy photosensitizers Methylene Blue, Azure C, Methylene Violet, Thionine, Methylene Green, Haematoporphyrin, Nile Blue A, chloroaluminium phthalocyanine and bis-aluminium phthalocyanine were examined for their photoeffects and dark toxicity against a human superficial bladder carcinoma cell-line. By examination of [3H]thymidine uptake into dye-treated cells after irradiation with a copper-vapour pumped dye laser, it was found that Methylene Blue was the most phototoxic and dark toxic of all the dyes tested, suggesting that the dye might be of some use as a topically applied photodrug for use in photodynamic therapy of superficial or early-recurring carcinomas.

Cell Adhesion↗

PubMed1990

Interleukin-2 and cancer therapy.

In summary, this meeting provided a useful overview of state-of-the-art research on IL-2. Significant gains have been made toward understanding the molecular biology and function of IL-2 and its receptors, but much remains to be learned about the intracellular signaling pathway by which IL-2 transduces its biological effects. Likewise, the nature of the lymphocyte subpopulation that responds to IL-2 requires detailed study, since it is now clear that T cells as well as LGLs can mediate non-MHC-restricted killing of tumor cells. Cell trafficking and effector cell activity within the tumor are other important issues to address. We also need to define the mechanism(s) by which IL-2-activated lymphoid cells mediate their antitumor effect in vivo; it is still far from clear whether these cells directly lyse the tumor cells, interrupt the tumor's vascular supply through endothelial cell damage, or produce other cytokines which then activate other cellular pathways. Preclinical data indicate that IL-2, with or without adoptive cellular therapy or in combination with other cytokines or drugs, can cause tumor regression. The success with animal model systems, however, has not always translated to success in the clinical setting-disappointingly, the majority of cancer patients still fail to respond to this treatment. It is hopeful the reasons for this will become apparent as more is learned about the molecular and cellular mechanisms involved in this "new" form of immunotherapy.

Clinical Trials as Topic↗

PubMed1989

The influence of interferon alpha and gamma, singly or in combination on human natural cell mediated cytotoxicity.

The influence of interferon alpha and gamma alone or in combination on the augmentation of human natural cytotoxicity was studied. Treatment of peripheral blood lymphocytes with IFN- alpha led to a rapid augmentation of NK activity, in contrast to IFN-gamma where target cell killing was observed only following 18 hrs exposure of lymphocytes to IFN-gamma. The results of the single cell assay paralleled those obtained using the Chromium release test, but neither interferon type caused an increase in the number of target binding lymphocytes. The combined effect of IFN-alpha and IFN-gamma in stimulating human natural cytotoxicity demonstrated individual lymphocyte responses to be variable. Exposure of lymphocytes to IFN-alpha and IFN-gamma for 18 hrs prior to assay for cytotoxicity usually decreased the level of cytotoxicity compared with control values, whereas other treatment regimes gave an additive and sometimes synergistic effect. Only treatment with IFN-alpha for 18 hrs and IFN-gamma for one hr produced a synergistic response in the majority of individuals tested. We conclude from this study that individual responses to IFN-alpha and IFN-gamma alone or in combination are variable and dependent upon timing of exposure of lymphocytes to individual interferon types, and possibly reflects the donor status at the time of sampling.

Cytotoxicity, Immunologic↗

PubMed1989

In vivo tumour x host cell fusion in spontaneous Syrian hamster metastasis.

The HSV-2 tumour system was originally derived from an in vitro transformation of HEF by inactivated HSV-2. When injected s.c. these cells produce spindle-cell sarcomas which are metastatic at a low level. Detailed cytogenetic studies have provided evidence of tumour x normal host cell fusion in two of seven cell lines derived from metastatic lung deposits (Met D and Met G). This is the first report, in an unselected, intraspecific system, of in vivo cell fusion in spontaneous metastasis. The cells of Met D consisted of a heterogeneous population of fused and unfused tumour cells, whereas those of Met G were a homogeneous population of hybrid cells. Fusion, therefore, is likely to have occurred after metastasis in Met D and prior to, or at, metastasis in Met G. The fused cells of Met D showed comparatively little chromosome loss, while in Met G there was loss of approaching one haploid set of chromosomes. The generation of metastatic variants by cell fusion contributes to genetic diversity and emphasizes the importance of tumour heterogeneity in malignancy.

Animals↗

PubMed1989

Estimation of DNA content in uveal melanomas by flow cytometry.

Flow cytometry was used to evaluate ploidy and tumour cycle kinetics in fresh tissue samples obtained from 19 uveal melanomas. The results were compared with other parameters including, histological cell type, tumour size and anatomical location. Three tumours (15.8%) were aneuploid (two mixed cell, one epithelioid cell). Cell turnover was estimated in the 16 diploid tumours by summating the total percentage of cells in S and G2/M phases. We found the mean percentage of cells in G2/M/S to be 5.96% (range 2.2-9.8%). Spindle cell neoplasms appeared to have lower cell turnover rates (4.5 +/- 1.2%) than epithelioid cell turnover (8.4 +/- 1.2%). There was no correlation between cell turnover and either tumour size or anatomical location.

Aged↗

PubMed1989

Inhibition of pregnancy viability in mice following IL-2 administration.

The influence of administration of interleukin-2 (IL-2) on syngeneic and allogeneic murine pregnancy has been investigated. Human or mouse recombinant IL-2 (rhIL-2 and rmIL-2), or partially purified rat IL-2, was inoculated i.p. into C57B1 mice following syngeneic mating but before embryo implantation. This inhibited subsequent fetal development in up to 100% of cases, compared with mice inoculated with control material, including recombinant human interleukin-1 alpha (IL-1 alpha), where no inhibition of pregnancy viability was observed. Similar data were obtained in both syngeneic and allogeneic matings when rhIL-2 was administered on Day 1 of pregnancy. Administration of rhIL-2 during the second pregnancy, rather than a first pregnancy, was less effective. Administration of rhIL-2 during the first pregnancy does not induce a permanent sterility. Histological examination of the endometrium further demonstrated that mice injected with rhIL-2 on Day 1 of their first pregnancy showed a complete absence of embryonic tissue.

Animals↗

PubMed1988

Comparison of excision versus cryosurgery of an HSV-2-induced fibrosarcoma. I. Survival, extent of metastatic disease and host immunocompetence following surgery.

Cryosurgery and excision were used to treat primary tumours of HSV-2-transformed hamster tumour sublines, and post-operative survival and the extent of metastatic disease were compared in the two groups. An inferior prognosis was observed following cryosurgery although the extent of metastatic disease was similar in both groups. Using this model it would appear that cryosurgery enhances the development of micrometastases rather than affecting the number of cells shed from the primary tumour during surgery. To investigate the underlying causes of the decrease in survival following cryosurgery, in vitro assays were used to monitor host immunocompetence following surgery. The results showed that whilst natural killer cell cytotoxicity was only marginally depressed, mitogen responsiveness and lymphocyte participation in a mixed lymphocyte reaction were severely reduced 3-7 days post-cryosurgery. In parallel with immunosuppression, extensive cell proliferation in the spleen of cryosurgically treated tumour-bearing animals was observed. Histological examination of the spleen demonstrated the presence of large numbers of transformed cells which correlated with the loss of mitogen responsiveness and the ability to participate in a mixed lymphocyte reaction. Further studies (manuscript submitted for publication) have demonstrated that spleen cells from animals whose tumour is treated by cryosurgery are capable of suppressing immunocompetence in vitro, implying they have a role in the uncontrolled growth of micrometastases in vivo.

Animals↗

PubMed1988

Characterisation of suppressor cells generated following cryosurgery of an HSV-2-induced fibrosarcoma.

Cryosurgery of a primary HSV-2-induced hamster fibrosarcoma resulted in the generation of a population of suppressor cells. These cells were detectable in the spleen 1-10 days post-cryosurgery by their ability to suppress the proliferation of immunocompetent splenic T-lymphocytes following exposure to concanavalin A (Con A). The spleens of tumour-bearing (t.b.) animals which received cryosurgery 3 days previously displayed gross splenomegaly due to the generation of large numbers of highly proliferative erythroblasts. The erythroblast cells were unlikely to be the source of suppression since time course studies have demonstrated the presence of suppressor cells before and after their appearance in the spleen. The erythroblasts therefore probably reflected a response by the host to regenerate the erythrocytes lost during surgery and their presence was independent of the appearance of suppressor cells. Characterisation of the suppressor cell has revealed it to be non-adherent and esterase negative making it unlikely to be of macrophage (MO) lineage. This was confirmed by the ability of splenic MOs from day 3 t.b. cryosurgery-treated animals to completely restore Con A-dependent T-lymphocyte proliferation following MO depletion. As nylonwool column-eluted cells are able to suppress Con A-dependent T-lymphocyte proliferation, it seemed unlikely that B-lymphocytes play a role in cryosurgery-induced immunosuppression. These findings suggest that cryosurgery of a t.b. animal results in the generation of a population of T-lymphocytes capable of suppressing Con A-dependent T-lymphocyte proliferation, and infers that these cells contribute to the inferior prognosis following cryosurgery as compared to excision of a metastatic tumour.

Animals↗

PubMed1988

Modulation of type IV collagenase and plasminogen activator in a hamster fibrosarcoma by basement membrane components and lung fibroblasts.

The effect of basement membrane components (laminin, fibronectin and type IV collagen) and lung fibroblasts on type IV collagenase and plasminogen activator activity was investigated in a primary HSV-2-induced hamster fibrosarcoma, and its in vivo derived sublines and in vitro derived clones of varying metastatic potential. Fibronectin and type IV collagen were ineffective at influencing the expression of either type IV collagenase or plasminogen activator activity. Laminin, however, at concentrations of 1-10 micrograms ml-1 added to the serum-free culture supernatants, increased the release of type IV collagenase by up to 100% for the parental cell line. Three highly metastatic sublines (two from in vivo origin and one from in vitro cloning) showed increases of up to 300%. Non-metastatic sublines (two from in vivo origin and one from in vitro cloning), however, showed no increase in type IV collagenase activity. Plasminogen activator release from either the parental line cell or its metastatic sublines and clones, was unaffected by the addition of laminin. Addition of tumour cells to lung fibroblast monolayers resulted in an increased expression of PA activity in the supernatant, whilst type IV collagenase activity was reduced.

Animals↗

PubMed1988

Loss of polymorphic A and B locus HLA antigens in colon carcinoma.

In the present study we have confirmed that approximately one third of human colorectal carcinomas fail to express the HLA - A,B,C monomorphic determinant reactive with the W6/32 MAb, and 44% express class II HLA antigens as shown by reactivity with NFK-1 MAb. Reduced staining with the W6/32 MAb was not always associated with the loss of beta 2m. In addition, the expression of HLA-A2 and Bw4 class I specific haplotypes on normal colon epithelium and tumour biopsy tissue was assessed. All normal colonic epithelia stained positively with MAb against A2 and Bw4 antigens, but a loss of these determinants was shown on tumour biopsies from patients tissue typed for the respective specificities. Loss of the A2 haplotype was shown in 4 of 15 tumour tissue samples, and loss of Bw4 specificities in 5 out of 7 tissue samples. The failure to detect specific loci determinants was not necessarily associated with loss of reactivity with W6/32 MAb.

Adenocarcinoma↗

PubMed1988

Human recombinant IL-4 suppresses the induction of human IL-2 induced lymphokine activated killer (LAK) activity.

The effect of recombinant human interleukin 4 (rhIL-4) on the induction in vitro of human lymphokine activated killer cell (LAK) activity was investigated. Peripheral blood mononuclear cells (PBMC) from normal healthy donors were incubated for 4 days with or without recombinant human interleukin-2 (rhIL-2) in the presence or absence of rhIL-4. LAK activity was measured against the NK-resistant colon adenocarcinoma cell line SW742, and NK mediated cytotoxicity was determined using NK sensitive K562 cells. Unlike previous reports using mouse effector cells, rhIL-4 neither induced LAK activity nor augmented the cytotoxic response induced by rhIL-2. In four out of six experiments there was a significant reduction of rhIL-2 induced LAK in the presence of rhIL-4, accompanied by a reduction of Tac antigen expression by rhIL-2 activated cells. Recombinant hIL-4 failed to influence the effector phase of the activated PBMC against SW742 or K562 targets.

Cytotoxicity, Immunologic↗

PubMed1988

The identification of factors in seminal plasma responsible for suppression of natural killer cell activity.

We have identified two components of human seminal plasma which suppress natural killer (NK) cell activity in vitro. Dialysis and gel filtration experiments have shown both components to be of low molecular weight. The first will suppress NK cells following a short period of pretreatment, but this suppression is dependent upon the presence of bovine serum in the medium and is directly related to a loss of cell viability as measured by trypan blue dye exclusion. We suggest that this molecule is a polyamine. The second factor will not suppress NK activity following pretreatment of lymphocytes, but is a potent suppressor when added for the duration of the assay. This suppression is completely bovine serum independent, unrelated to toxicity and appears to be mediated by prostaglandin E2. The relevance of these results to a clinical situation is discussed.

Chromatography, Gel↗

PubMed1987

Type IV collagenase activity of a primary HSV-2-induced hamster fibrosarcoma and its in vivo metastases and in vitro clones.

The expression of a basement membrane (BM) collagen-degrading metalloprotease (Type IV collagenase) was studied in a herpes simplex virus (HSV)-2 transformed hamster fibrosarcoma and its in vivo derived sublines and in vitro derived clones of varying metastatic potential. The primary parent tumor was shown to release more or less Type IV collagenolytic activity compared with its sublines (derived from lung nodules that developed after resection of the primary tumor). Normal baby hamster kidney and hamster embryo fibroblasts did not secrete detectable amounts of BM collagenase, whereas normal hamster lung fibroblast secreted intermediate levels of Type IV collagenase activity. The collagenase IV activity of the parent tumor and its in vivo and in vitro derived sublines was assayed in vitro and compared with the ability of the cells lines to spontaneously metastasize in vivo. No correlation between the ability to secrete type IV collagenase and metastatic propensity was detected. Although all cell lines secreted type IV collagenase, the highest activity was recorded for a nonmetastatic variant.

Animals↗

PubMed1987

Evidence for the involvement of calmodulin in natural cytotoxicity using a range of calmodulin antagonists of varying potency and improved specificity.

The calmodulin antagonist W7 and 4 of its analogues were examined for their ability to inhibit human NK cell mediated cytotoxicity. With the exception of one of these compounds, which is extremely hydrophobic, there was a good correlation between the ability of drugs to inhibit human NK antitumour cytotoxicity and calmodulin-dependent phosphodiesterase activity in vitro. The most potent of the compounds, 5-iodo-1-C8, an analogue of W7, has an IC50 of 3 microM upon biological and biochemical assay. This particular compound is both more potent and specific than the parent compound W7, is non-toxic to cells over the range used and is also capable of inhibiting the biological activity of NK cells upon pre-treatment of the effector cells, inferring the mechanism of NK cytotoxicity to be calmodulin dependent.

Calmodulin↗

PubMed1987

Spontaneous natural killer cell activity in childhood acute lymphoblastic leukaemia.

Endogenous NK activity was measured in ALL patients and compared with child and adult control values. ALL children undergoing maintenance chemotherapy showed significantly lower NK activity than control groups; however, patients off treatment and in remission expressed cytotoxicity within the normal range of the control groups. The expression of the HNK-1 marker in the ALL children was not significantly different from child controls, although ALL patients failed to show the same correlation between cytotoxic activity and HNK-1 expression. The target binding capacity of PBLs from ALL children was significantly greater compared with controls but did not correlate with NK activity. In addition plasma from ALL patients was not inhibitory for NK cytolytic activity, suggesting an innate defect in cytotoxicity mediated by NK cells rather than a plasma inhibitory factor. Patients failing to display NK activity against K562 target cells appeared to mediate killing of measles virus infected (Raji) targets.

Adolescent↗

PubMed1987

Immunomodulation of natural killer activity in children with acute lymphoblastic leukaemia.

Modulation of NK activity of PBLs from ALL patients was studied following exposure to IFN-alpha, staphylococcal protein A and interleukin-2. Only 52% of ALL patients responded to IFN-alpha stimulation, where the majority of controls showed positive enhancement of NK activity. Protein A failed to cause a significant stimulation of ALL patient PBLs whereas all controls showed a positive response. The majority of ALL patient and child control PBLs were however able to produce significant levels of IFN-gamma (protein A stimulation) and IFN-alpha (Sendai virus stimulation), although significantly more of both types of interferon could be induced in adult PBL samples. The ability of IL-2 to activate NK activity of ALL PBL samples showed a similar trend to IFN-alpha stimulation; thus, not all ALL patients showed positive augmentation of NK activity upon IL-2 stimulation. It is clear from these results that interferons and IL-2 may not necessarily lead to activated NK cytolytic activity, and in the present study approx. 50% of ALL patients failed to respond to lymphokine stimulation.

Adolescent↗

PubMed1987

The effect of the immune status of the TAR mouse on the growth and metastasis of tumour xenografts.

Mice thymectomised at 3-4 weeks of age and subsequently given whole-body irradiation (9 Gy) under cytosine arabinoside cover (TAR mice) provide an alternative model to the athymic nude (nu+/nu+) mouse for studying the biological characteristics of tumour xenografts. In the present study we have evaluated the repopulation events in the bone marrow and spleen following whole body irradiation of TAR mice, and analysed immune competence up to 98 days following irradiation. Repopulation of both bone marrow and spleen was evident in the weeks following whole body irradiation, and an initial increase in the relative proportion of T-lymphocytes present in the spleen was followed by a decrease in the percentage of lymphocytes expressing T-cell markers, which remained below the level observed in control mouse spleen cell preparations. TAR mice exhibited a decreased ability to respond to a non-specific T-cell mitogen and to elicit a T-cell dependent antibody response to influenza viral antigen. Both TAR and control mice possessed macrophages which could be activated to the tumouricidal state, and natural killer activity of TAR mice was enhanced greater than 3-fold above control values. The ability of TAR mice to accept tumour xenografts decreased with the increasing time interval between irradiation and subcutaneous implantation of tumour cells, and (in some instances) spontaneous regression was observed. In addition, a hamster tumour cell line possessing high metastatic potential in its syngeneic host was shown to metastasise to the regional lymph node, lungs, liver, kidneys and spleen of TAR mice from a cell inoculum implanted subcutaneously immediately after irradiation; however, with increasing time between irradiation and inoculation of tumour cells tumour metastasis decreased. The ability of TAR mice to support the growth and metastasis of tumour xenografts would appear to inversely correlate with the increase in natural killer cell activity following irradiation.

Animals↗

PubMed1987

Therapy of spontaneously metastatic HSV-2 induced hamster tumours with cortisone acetate administered with or without heparin.

Subcutaneous injection of cortisone acetate administered with or without oral heparin retarded the growth of two HSV-2 induced hamster fibrosarcomas. Histological sections showed no obvious difference between the vasculature of treated and untreated tumours although there were fewer infiltrating lymphocytes in treated tumours. Treatment was, however, found to be ineffective against metastatic development following resection of primary tumours. Natural killer cell activity was found to be greatly reduced in animals receiving heparin and/or cortisone acetate treatment and this may influence the effectiveness of treatment on the metastatic process. We conclude that treatment of tumours with cortisone plus heparin is no different from the response to cortisone used alone.

Animals↗