Biomedical subjects

Angus Dalgleish

Publications and source records attributed to Angus Dalgleish.

11 recordsLinked to original sources

PubMed2005

Cryopreserved dendritic cells for intratumoral immunotherapy do not require re-culture prior to human vaccination.

Dendritic cell (DC) immunotherapy for cancer has shown great promise so far. The ability to deliver dendritic cells directly into tumours where they are capable of acquiring tumour antigens prior to stimulating specific T cell responses has been demonstrated both in animal models and human patients. Clinical grade DCs can be grown from peripheral blood monocytes in the absence of foetal calf serum (FCS) and cryopreserved to generate plentiful identical aliquots thus avoiding repeated venesection. However, the approach is still limited by the necessity to return thawed DCs to culture prior to injection. It would be more advantageous to directly inject the DCs whilst still in the freezing medium and thus prevent the need for further manipulation. Whilst several reports have shown that cryopreserved DCs can survive for over 72 h when returned to culture, there is no information regarding the longevity of cells maintained in the freezing medium after thawing. In this report we have shown that DCs may remain in freezing medium for up to 1 h without affecting their survival, phenotype or function. This period of time is sufficient to allow for any delays incurred between the preparation of the DCs and time taken to be administered within a standard clinical setting. This study demonstrates that clinical grade DCs can be cryopreserved and thawed whilst retaining the ability to acquire exogenous antigenic material required for intratumoural immunotherapy. The survival of these cells within the freezing medium without the requirement for re-culture expands their availability for administration directly to the tumours of patients in non-specialist centres that do not have the appropriate facilities for DC re-culture.

Antigen Presentation↗

PubMed2005

Immunotherapy of murine prostate cancer using whole tumor cells killed ex vivo by herpes simplex viral thymidine kinase/ganciclovir suicide gene therapy.

Whole cell cancer vaccines are currently under clinical evaluation. Their immunogenicity may depend on the mode of death of the vaccine cells prior to uptake by professional antigen-presenting cells and crosspriming of T cells. Destruction of tumor in vivo by genetic prodrug activation therapy leads to a marked local and systemic immune response, local T-cell infiltration and the establishment of T-cell memory. We postulated that this immunostimulation may be due to induction of danger signals and the inherent immunogenicity of products of HSVtk/ganciclovir kill. Using established models of murine prostate cancer, we have evaluated the efficacy of anti-tumor vaccines comprising irradiated allogeneic or autologous whole cells expressing HSVtK, which are first killed in vitro by prodrug activation using ganciclovir. HSVtk/ganciclovir-induced cell kill was through the induction of apoptosis. The vaccine was found to be effective in both models and superior to traditional irradiated whole tumor cells even after single doses. Protection against tumor challenge was associated with marked proliferative and Th1 cytokine responses. This approach would be applicable clinically in terms of ease of vaccine production, safety, storage and avoidance of potential toxicities of in vivo gene transfer.

Animals↗

PubMed2005

Immunotherapy of murine prostate cancer using whole tumour cells killed ex vivo by cytosine deaminase/5-fluorocytosine suicide-gene therapy.

OBJECTIVE: To evaluate the efficacy of antitumour vaccines comprising irradiated allogeneic or autologous whole cells expressing cytosine deaminase (CD) which are first killed ex vivo by prodrug activation using 5-fluorocytosine (5-FC), as the immunogenicity of tumour cells used as irradiated vaccines depends both on antigen expression and on the mode of their death. MATERIALS AND METHODS: The PA3 rat prostate cell line and MATLyLu, an androgen-insensitive subline, were grown and transfected with CD (designated PCD and MCD). In vitro drug-sensitivity was assessed in the cell lines using a viability assay, and the mode of cell death quantified by assessing apoptosis. Bax and bcl-2 expression were assessed by Western blot analysis. For in vivo experiments, male 8-10-week-old Lobund-Wistar rats were vaccinated (using vehicle in control groups) with 5 x 10(6) cells, all cells being irradiated before injection, to give groups with PA3, PCD, PCD killed with 5-FC, MatLyLu, MCD, and MCD killed with 5-FC. After 7 days all animals were given a subcutaneous tumour challenge of PA3 cells, and tumour volume measured subsequently. Immune responses were assessed in splenocytes. RESULTS: The efficiency of cell kill varied between the cell lines assessed, but cell death was by induced apoptosis. Single doses of vaccine were most effective in the allogeneic setting, causing significantly slower growth of syngeneic tumour challenge (P < 0.01), and 25% better survival at 50 days (P < 0.02) than irradiated untransfected cells. This was consistent with the greater proliferative response after allogeneic than autologous vaccination. CONCLUSION: The immunogenicity of irradiated tumour cells is enhanced when they are killed ex-vivo using suicide-gene therapy. This approach would be clinically applicable in terms of ease of vaccine production, safety, storage and avoidance of potential toxicities of in vivo gene transfer.

Animals↗

PubMed2005

Novel immunotherapeutic approaches to prostate cancer.

Immunotherapy offers new and exciting therapeutic options for patients with late-stage prostate cancer. While the concept of using the immune system to combat cancer is not new, it is only in this post-genomics era that the realistic possibility exists of effectively harnessing the immune system against disease. Immunotherapies can be loosely divided into three major categories: non-specific immune stimulation, specific target antigens and whole-cell approaches. All three systems have merits and drawbacks, although the goal of overcoming 'self' tolerance is common to all of them. This review highlights some of the more recent experiments in each of these three fields, focusing particularly on prostate cancer. We suggest that it is unlikely that one single cancer antigen exists and that recent data support this by showing that strong immune responses to prostate antigens can be elicited in a variety of ways. Therefore, a multivalent approach is likely to be most clinically efficacious. Data gathered from the past three years are discussed in this review and lead to the inescapable conclusion that immunotherapy is now a reality.

Antigens↗

PubMed2004

Novel strains of Salmonella typhimurium as potential vectors for gene delivery.

DNA vaccines are known to induce long-term antigen specific cellular responses. We tested two new strains of Salmonella typhimurium, one carrying a mutation in a SPI-2 gene and the aroC-gene and another carrying mutations in the sifA- and aroC-genes, as potential DNA vaccine delivery vehicles. We compared them with the SL7207 strain and found that the new strains were more invasive, and that they were efficient mediators of gene transfer in vitro using EGFP as reporter gene. We tested the ability of the new strains to survive within the spleen, liver and mesenteric lymph nodes and evaluated their safety in C57/BL/6J mice.

Animals↗

PubMed2004

Differential expression of melanoma-associated antigens and molecules involved in antigen processing and presentation in three cell lines established from a single patient.

Tumour cells are able to evade the immune system by using several 'escape mechanisms'. Downregulation of molecules involved in the processing and presentation of self-antigens has been reported. However, these adaptations have not been compared in metastases in different anatomical locations but derived from a single patient. We investigated three melanoma cell lines--MJT1 from the parietal lobe of the brain, MJT3 from the cerebellum and MJT5 from the left side of the neck--established from biopsies excised from a 45 year old female patient. Although human leukocyte antigen (HLA) class I was detected in all three cell lines by flow cytometry using an anti-HLA monomorphic antibody, further serological analysis demonstrated HLA B38 loss in all three cell lines, HLA B7 downregulation in MJT5 (skin metastases) and B7 loss in MJT3 and MJT1 (brain metastases) compared with the HLA type of the patient's normal autologous lymphocytes. Interferon-gamma (IFNgamma) treatment increased the expression of HLA class I and transporters associated with antigen processing 1 (TAP1) in all three cell lines. De novo HLA class II molecule expression was observed after IFNgamma treatment in MJT3 and MJT5. Western blot and reverse transcription-polymerase chain reaction results revealed heterogeneity of melanoma-associated antigen (MAA) expression in the cell lines: MJT3 cells expressed higher levels of MAAs than the other two cell lines. In conclusion, this study has demonstrated that three metastatic lesions from a single patient can have differential expression of molecules involved in antigen processing (TAP1) and presentation (HLA I and II), but that expression of these molecules is modulated by IFNgamma to a similar degree in all cell lines. In contrast, the downregulation of expression of specific MAAs between the three cell lines was unaffected by the addition of IFNgamma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Melanoma vaccines.

Melanoma vaccines offer new hope to patients with metastatic melanoma, although convincing survival advantages have yet to be reported. This review outlines the progress made in this exciting field of research and looks ahead to the future.

Antigens, Neoplasm↗

PubMed2004

Prevention.

Explore the source record for details and available documents.

Health Promotion↗

PubMed2003

Cancer immunotherapy: an embarrassment of riches?

There is clear evidence that certain forms of immunotherapy can be successful against certain cancers. However, it would appear that cancerous cells of various origin are exceptionally adept at subverting the immune response. Consequently, it is probable that the most efficacious therapy will be one in which multiple responses of the immune system are activated. There is currently an embarrassment of riches with regard to multiple vaccine strategies in the clinic, although no single method seems to hold the solution. Here, we draw together several of the humoral- and cellular-activating strategies currently under clinical investigation.

Antigens, Neoplasm↗

PubMed2003

Cryopreservation of immature monocyte-derived dendritic cells results in enhanced cell maturation but reduced endocytic activity and efficiency of adenoviral transduction.

To date, phase I/II dendritic cell (DC)-based cancer vaccine trials have required repeated venesection or leukapheresis to generate the DCs. Previous studies have suggested that DCs may be cryopreserved and revived for clinical use as sequential immunisations. We have developed a method of cryopreserving monocyte-derived DCs, reviving the cells with minimal loss, and have performed immunophenotypic and functional comparisons of freeze-thawed DCs with their fresh counterparts. We found that the freeze-thawing process itself is efficient in terms of DC recovery, results in semimaturation and reduced endocytic activity, but does not impair the capacity of the DCs to achieve full maturation. Revived cells also showed enhanced allostimulatory activity and antigen-specific responses. After freeze-thawing, DCs produced lower levels of IL-12 p40 and IL-12 p70 on maturation compared to fresh DCs with little change in concentration over 72 h. Genetic modification of DCs by adenoviral transduction was possible after cryopreservation albeit at a lower efficiency of gene transfer than with fresh cells. We conclude that cryopreservation of DCs for clinical immunotherapy is feasible. Modification of cells by pulsing or genetic transfer should take place prior to cryopreservation as the freeze-thawing process itself leads to increased maturation, reduction in endocytic activity but enhanced allostimulatory activity and antigen-specific responses.

Adenoviridae↗

PubMed2002

Immunotherapeutic potential of whole tumour cells.

Despite the identification of tumour antigens and their subsequent generation in subunit form for use as cancer vaccines, whole tumour cells remain a potent vehicle for generating anti-tumour immunity. This is because tumour cells express an array of target antigens for the immune system to react against, avoiding problems associated with major histocompatibility complex (MHC)-restricted epitope identification for individual patients. Furthermore, whole cells are relatively simple to propagate and are potentially efficient at contributing to the process of T cell priming. However, whole cells can also possess properties that allow for immune evasion, and so the question remains of how to enhance the immune response against tumour cells so that they are rejected. Scenarios where whole tumour cells may be utilised in immunotherapy include autologous tumour cell vaccines generated from resected primary tumour, allogeneic (MHC-disparate) cross-reactive tumour cell line vaccines, and immunotherapy of tumours in situ. Since tumour cells are considered poorly immunogenic, mainly because they express self-antigens in a non-stimulatory context, the environment of the tumour cells may have to be modified to become stimulatory by using immunological adjuvants. Recent studies have re-evaluated the relative roles of direct and cross-priming in generating anti-tumour immunity and have highlighted the need to circumvent immune evasion.

Animals↗