Essential diseases in prescribing: A national Delphi study towards a core curriculum in pharmacotherapy education.

AIMS: Prescribing is a core skill for junior doctors, yet 8-10% of their prescriptions contain errors. To ensure adequate training in prescribing, it is important to define the diseases for which junior doctors should be competent to prescribe. The aim of the present study was therefore to identify the essential diseases in prescribing for junior doctors. METHODS: A two-round Delphi consensus study was conducted among medical specialists, general practitioners, junior doctors, pharmacists and pharmacotherapy teachers from all eight academic hospitals in the Netherlands. Using a five-point Likert scale, the participants indicated for each item on an initial questionnaire whether it should be considered an essential disease for junior doctors. The items for which ≥80% of all respondents agreed or strongly agreed were accepted as essential diseases. RESULTS: Sixty-two participants completed the Delphi survey. In total, 63 of 220 items were considered to be essential diseases. CONCLUSION: This is the first Delphi consensus study identifying exact conditions that junior doctors must be able to prescribe for. The essential diseases can be used for training in prescribing and assessment of junior doctors' prescribing competence.

Lack of effect of different cytokines on expression of membrane-bound regulators of complement activity on human uveal melanoma cells.

Tumor cells are protected from antibody-dependent complement-mediated lysis by membrane-bound regulators of complement activation (m-RCA). m-RCA are expressed on uveal melanoma cells. We determined whether cytokine treatment affects expression of m-RCA on these cells in vitro. m-RCA expression on uveal melanoma cell lines was studied by flow cytometry, using monoclonal antibodies directed against CD46, CD55, and CD59. Cytokines studied were interferon-alpha (IFN-alpha), IFN-gamma, interleukin-1B (IL-1B), IL-12, and tumor necrosis factor-alpha (TNF-alpha). All three m-RCA were expressed on the uveal melanoma cell lines (CD59>>CD46>CD55), although in variable amounts. With a few exceptions, the cytokines had no effect on m-RCA expression. CD55 expression was not influenced by any of the cytokines. IFN-gamma downregulated expression of CD46 on one cell line (p < 0.01). TNF-alpha upregulated CD59 expression on two of the five cell lines (p < 0.012 and p < 0.001, respectively), which effect was dose dependent. IFN-alpha, IFN-gamma, IL1-beta, IL12, and TNF-alpha had limited effects on m-RCA expression on uveal melanoma cells in vitro.

Membrane-bound regulators of complement activation in uveal melanomas. CD46, CD55, and CD59 in uveal melanomas.

PURPOSE: To identify the presence of membrane-bound regulators of complement activation (m-RCA) on uveal melanomas and uveal melanoma cell lines and to examine their role in the inhibition of complement-mediated lysis in vitro. METHODS: Immunohistochemistry and flow cytometric analysis with monoclonal antibodies directed against m-RCA CD46, CD55, and CD59 were applied to tissue sections of 10 uveal melanomas, three primary uveal melanoma cell lines, and one uveal melanoma metastatic cell line. A microcytotoxicity test was used for measuring antibody-dependent complement-mediated lysis. RESULTS: The tissue sections and all four uveal melanoma cell lines expressed CD46, CD55, and CD59. Complement-mediated lysis in the presence of human complement was increased after partial removal of the m-RCA CD55 and CD59 with phosphatidylinositol-specific phospholipase C from the uveal melanoma cell line 92-1. CONCLUSIONS: These results demonstrate that CD46, CD55, and CD59 are expressed in uveal melanomas and that CD55 or CD59, or both, plays a role in resistance to complement-mediated cytotoxicity. The finding that m-RCA are expressed in uveal melanomas may have implications for the effectiveness of the anti-tumor response and in the therapeutic application of monoclonal antibodies directed against tumor-associated antigens.

Multidrug resistance-related proteins in primary choroidal melanomas and in vitro cell lines.

PURPOSE: Metastatic uveal melanoma is strongly resistant to chemotherapy, and multidrug resistance (MDR) may be involved. To investigate the role of MDR, the presence of the MDR-associated proteins P-glycoprotein (Pgp), MRP, and lung resistance protein (LRP) was determined on primary choroidal melanomas and cell lines. METHODS: A panel of primary choroidal melanomas was examined for the presence of MDR-associated proteins by immunohistochemical analysis. In cell lines established from four primary choroidal melanomas and one metastatic choroidal melanoma, the expression of MDR-associated proteins was determined with monoclonal antibodies in cytospin preparations and flow cytometry. In addition, the functional capacities of transporter proteins Pgp and MRP as adenosine triphosphate-driven efflux pumps were determined by measuring the cellular accumulation and efflux of the fluorescent dyes rhodamine 123 and calcein-AM, with and without the presence of specific pump inhibitors PSC833 and probenecid. RESULTS: Low levels of Pgp and MRP were detected in most primary tumors and in some cell lines. Measurable transporter function of Pgp could be determined in cell line OCM-1. Lung-resistance protein was present in all primary tumors and cell lines and showed high expression levels. CONCLUSIONS: This study revealed the involvement of LRP and at least a minor role of Pgp and MRP in chemoresistance of choroidal melanoma. Compared with cutaneous melanomas, uveal melanomas appear to express slightly higher levels of Pgp. These findings provide insights into the drug-resistant phenotype of this disease and can aid in the design of therapeutic protocols.

HLA antigen expression on uveal melanoma cells in vivo and in vitro.

Immunotherapy with cytokines may be an additional option in the treatment of primary uveal melanoma or melanoma metastases. A study of the effect of cytokines on cultured uveal melanoma cells may predict the effect that cytokines may have in vivo. Knowledge about the influence of cytokines on HLA expression may be especially beneficial, as HLA expression is essential for immune recognition. However, little is known about the normal expression of the HLA antigens on uveal melanoma cells in tissue culture. We therefore determined the HLA expression on short-term cultures of uveal melanoma cells and compared the results to the expression on tissue sections of the original tumors. In vivo and in vitro expression of the monomorphic HLA class I determinants and of HLA-A (R = 0.77) correlated well. A slightly lower agreement was observed for expression of HLA-B (R = 0.68). In vitro growth was associated with a decrease in expression of the class II determinant HLA-DR. We conclude that expression of HLA class I on cultured melanoma cells corresponds to the expression on the original tumor, allowing the applicability of cultured cells as predictors of responsiveness to cytokines in vivo.

Decreased expression of HLA class I on ocular melanoma cells following in vitro photodynamic therapy.

Our objective was to investigate whether photodynamic therapy (PDT) influences the expression of HLA Class I and beta 2-microglobulin molecules on cultured uveal melanoma cells. Uveal melanoma cells were incubated with hematoporphyrin esters (HPE) and illuminated using red light. HLA expression on cells was determined by flowcytometry. PDT treatment induced an immediate reduction in expression of HLA Class I and beta 2-microglobulin, followed by a transient increase in expression after 2 h. Normalization occurred after 6 h. Treatment of ocular melanoma cells with PDT temporally alters the expression of HLA Class I and beta 2-microglobulin, which may affect anti-tumor-immune responses.

Effects of interferon alfa and gamma on human uveal melanoma cells in vitro.

BACKGROUND: Uveal melanoma is a tumour with a high incidence of metastasis and a high mortality rate. Additional therapies to obtain a better local control or an effective treatment of metastases are necessary. Interferons may be applied. METHODS: The effects of human interferon alfa and gamma on proliferation and expression of immunologically important molecules of human uveal melanoma cells in vitro were studied. A propidium iodide assay was used to determine proliferation and immunostaining with monoclonal antibodies was applied to detect changes in antigen expression on two primary uveal melanoma cell lines, Mel 202 and 92-1. RESULTS: Interferon alfa inhibited proliferation of cell line 92-1 at a concentration of 50 IU/ml, but had no effect on cell line Mel 202, while interferon gamma inhibited growth of both cell lines. Only interferon gamma had a visible effect on cell morphology. With respect to the immunomodulatory effects, interferon alfa increased monomorphic HLA class I expression, but did not affect HLA class II expression. Interferon gamma induced not only HLA class I but also class II expression. The effects on HLA expression were locus-specific with the strongest effects observed for HLA-B and DR products. Small differences were observed with respect to the susceptibility of two different melanoma cell lines to antiproliferative effects and to modulation of antigen expression. CONCLUSION: The effects of interferon alfa and gamma on human uveal melanoma cells in vitro suggest a potential role of these cytokines in the treatment of patients with uveal melanoma. In particular, the immunomodulatory effects of these cytokines in vitro imply that treatment of patients with these cytokines might stimulate a beneficial antimelanoma immune response in vivo.

HLA expression in a primary uveal melanoma, its cell line, and four of its metastases.

BACKGROUND: The level of HLA expression on a tumour may influence the immunological response against this tumour, and vice versa. HLA expression was determined in a primary uveal melanoma, its metastases, and on a cell line derived from this melanoma, and the presence and type of infiltrate in tissue sections were also studied. METHODS: Immunohistochemistry with monoclonal antibodies (MAbs) against HLA class I and II, T cells, NK cells, and macrophages. RESULTS: Primary and metastatic lesions, as well as the cell line showed high levels of expression of the monomorphic determinants of HLA class I. Expression of the polymorphic HLA-A2 and HLA-A3 antigens was decreased on metastases to the skin and liver. HLA-Bw4 expression was low on all lesions, as well as expression of HLA class II. Tumour infiltrating cells consisted mainly of CD3, CD4, and CD8 positive cells. Expression on the cell line corresponded to expression on the primary tumour. CONCLUSION: The primary uveal melanoma as well as the cell line showed a high expression of monomorphic and polymorphic HLA-A antigens, while metastases showed a high expression of monomorphic and a lower expression of polymorphic antigens. This variation in expression may support tumour cell escape from NK cells as well as CTL mediated lysis.

Cytokine-mediated modulation of integrin, ICAM-1 and CD44 expression on human uveal melanoma cells in vitro.

Adhesion molecules are likely to play a role in the process of tumour progression. We investigated the expression of integrins, ICAM-1, and CD44 and the influence of interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), and tumour necrosis factor-alpha (TNF-alpha) on expression of these molecules on four uveal melanoma cell lines. The in vitro integrin expression was quite variable. The alpha V and beta 1 subunits were expressed on all cell lines, and none of the cell lines showed any alpha 3, beta 2, or beta 4 expression. Other integrin subunits showed a more variable pattern. ICAM-1 and CD44 were strongly expressed on all cell lines. IFN-alpha, IFN-gamma, and TNF-alpha upregulated alpha 1, alpha 2, and alpha 3 expression, and did not alter alpha 4, alpha 5, alpha 6, beta 2, alpha v beta 3, and beta 4 expression. The effects on alpha V and alpha V beta 5 were variable. ICAM-1 was upregulated by IFN-gamma and TNF-alpha, but not by IFN-alpha. Cytokine treatment hardly changed CD44 expression. In one case a comparison was made between expression on cultured cells and on tissue sections of the tumour of origin. Differences in expression were observed for the integrin subunits alpha 2, alpha 3, and alpha 5. This study shows that integrins and ICAM-1 expression on uveal melanoma cells in vitro are susceptible to cytokine treatment, but that the effects on integrin expression are cytokine and cell line dependent. Furthermore, some differences in integrin expression between cells in vivo and in vitro exist.

Effects of transpupillary thermotherapy on immunological parameters and apoptosis in a case of primary uveal melanoma.

Transpupillary thermotherapy (TTT) is a new treatment modality for uveal melanoma. We studied whether application of TTT influences the immunogenicity of the tumour cells in vivo or the expression of molecules related to apoptosis. Immunohistochemistry using monoclonal antibodies directed against HLA molecules, HMB45, P53, Fas ligand (FasL), Fas, Bcl-2 and tumour-infiltrating cells was applied to sections of an enucleated eye containing a uveal melanoma that received TTT 1 week before enucleation. The innermost part of the tumour which had been exposed directly to the laser treatment showed no staining for HLA antigens, nor for Fas or FasL epitopes. The intermediate part of the tumour showed a wet necrosis and HLA expression similar to the expression in the peripheral tumour. A large number of macrophages were observed in the necrotic as well as the intact tumour tissue, especially bordering the wet necrotic area. FasL and Bcl-2 were only expressed in the viable, outer part of the tumour. This immunological evaluation of one case of uveal melanoma treated with TTT revealed that TTT may not only have a direct destructive effect on the primary tumour, but may also influence the immunogenicity of uveal melanoma cells, induce infiltration of macrophages into the tumour, and induce apoptosis. The presence of many macrophages suggests that they play a role in the removal of the TTT-treated tumour tissue by phagocytosis.

Effect of hyperthermia on expression of histocompatibility antigens and heat-shock protein molecules on three human ocular melanoma cell lines.

Hyperthermia is used as a new treatment modality for ocular melanoma. We wondered whether this treatment would affect the antigenicity of melanoma cells and studied the effect of hyperthermia on the expression of histocompatibility antigens (HLA), beta 2-microglobulin, as well as heat-shock proteins (HSP-60 and HSP-70) on choroidal melanoma cells. Uveal melanoma cell lines were exposed to different temperatures (39-45 degrees C) in a waterbath. Antigen expression was determined with fluorescence-activated cell sorting analysis, using monoclonal antibodies against HLA and HSP. In a 51Cr-release cytotoxicity assay we studied the effect of heat on natural killer (NK) cell susceptibility. Exposure to 45 degrees C for 30 min reduced expression of HLA class I antigens and beta 2-microglobulin. A greater reduction was observed after longer exposure times. Expression of HSP-70 was increased after exposure to 45 degrees C at all time intervals, while expression of HSP-60 was not induced by heat treatment. We did not find a significant difference in the NK cell susceptibility between heated and unheated cells. Hyperthermia has a time- and temperature-dependent effect on expression of HLA class I and HSP-70 molecules on the cell surface of uveal melanoma cells. Hyperthermia did not alter the susceptibility to NK cell lysis.

Expression of MAGE, gp100 and tyrosinase genes in uveal melanoma cell lines.

In order to determine the possible use of uveal melanoma cell lines as stimulators in immunotherapy, we evaluated the expression of the human genes for MAGE-1, -2 and -3, gp100 and tyrosinase in uveal melanoma cell lines. mRNA expression of the MAGE-1, -2 and -3, gp100 and tyrosinase genes and the HLA class I specificity were determined in five primary and three metastatic uveal melanoma cell lines. Expression of the examined genes was heterogeneous in the primary and metastatic cell lines. The cell lines OCM-1 and OMM-1 expressed MAGE-1, -2 and -3, whereas EOM-3, MEL202, 92-1 and OMM-3 were negative for these antigens. gp100 was expressed in all cell lines, and tyrosinase in all but three (EOM-29, OMM-2 and OMM-3). Except for EOM-3, the HLA-A type of all the cell lines could be determined by complement-dependent microlymphocytotoxicity assay. Since at least two melanoma-associated antigens can be found in uveal melanoma cell lines, as well as the HLA class I molecules, these cell lines may be applicable as immunogens for specific immunotherapy against metastatic uveal melanoma.

Differential expression of HLA-A and B-alleles on uveal melanoma as determined by immuno-histology.

HLA molecules play an important role in the presentation of antigens to the immune system, including tumor-specific antigens. Uveal melanomas vary in the level of expression of monomorphic HLA molecules. However, since the HLA system is polymorphic and since antigen-presentation may be linked to the expression of specific HLA alleles, the authors wondered whether allelic differences in expression existed on uveal melanomas. In order to test this, tissue sections from 23 uveal melanomas were stained in an indirect immunoperoxidase technique with monoclonal antibodies against monomorphic and polymorphic determinants of HLA molecules. All uveal melanomas showed a high level of expression of the monomorphic determinants of HLA-Class I. The polymorphic HLA-Class I molecules A2, A3, Bw4 and Bw6 varied in expression, with a higher expression of HLA-A than of HLA-B. A low level of expression of both ß2-microglobulin and HLA-B locus products was associated with a large tumor diameter. Expression of HLA-Class II molecules was low (0 to 35%). The observation that expression of the HLA-A allelic products was higher than of the HLA-B subtypes may have implications for the search of tumorspecific peptides for immunotherapeutic use: it may be worthwile to select peptides that specifically bind to HLA-A and not to HLA-B.

Hamster Greene melanoma in the rabbit eye: immunosuppressive treatment to improve this tumor model.

BACKGROUND: The hamster Greene melanoma (HGM) implanted in the anterior chamber of the rabbit eye has been used to study experimental therapies for human uveal melanoma. However, the occurrence of spontaneous necrosis limits the value of this model for long-term evaluation of experimental treatments. In the present study we tested the hypothesis that an immune response is the cause of this necrosis and that prevention of the immune response can prolong the experimentation time METHODS: HGM was implanted in the anterior chamber of control, presensitized and immunosuppressed rabbits. The effects of sensitization and immunosuppression were assessed by clinical and histological observation RESULTS: Sensitization led to a significant slowing down of tumor growth, but not to a difference in necrosis. Immunosuppressive treatment with cyclosporin A improved the success rate of implantation and decreased the amount of necrosis in the tumor CONCLUSION: The immune response plays a role in the occurrence of necrosis. However, although immunosuppressive treatment with cyclosporin A decreased the amount of necrosis, significant necrosis still occurred, suggesting that other factors like angiogenesis play a part as well and still limit the usefulness of this model in the long-term evaluation of experimental therapies.

HLA expression and tumor-infiltrating immune cells in uveal melanoma.

BACKGROUND: In uveal melanoma, both the amount of tumor-infiltrating cells and the level of expression of HLA antigens are quite variable. We hypothesized that low levels of HLA expression lead to a lack of antigen presentation, which might prevent proper immunologic recognition of the tumor. This lack of recognition might subsequently lead to low levels of tumor-infiltrating cells. METHODS: To test this hypothesis, we determined the type and number of tumor-infiltrating cells in tumor sections from 24 uveal melanomas. We applied monoclonal antibodies directed against different types of immune cells and compared the results with the expression of HLA class I and class II antigens on the tumor cells. RESULTS: Infiltrating immune cells were observed in all uveal melanomas (although in small amounts), with a predominance of T lymphocytes. Significant positive correlations were observed between the number of CD3+ cells (T lymphocytes) and monomorphic HLA class I expression, allele-specific HLA-A2 and Bw4 expression, and HLA class II expression. Furthermore, the number of CD4+ cells (T helper cells, monocytes/ macrophages) and of CD11b+ cells (monocytes/macrophages) was significantly correlated with the level of monomorphic HLA class I expression. CONCLUSION: These data support our hypothesis that low levels of HLA expression (and therefore a lack of presentation of tumor-specific antigens) may lead to a low level of tumor infiltrate.

Establishment and characterization of an uveal-melanoma cell line.

A human uveal melanoma cell line (92-1) was established from a primary uveal melanoma, and has now been maintained in culture for over 2 1/2 years. Light microscopy of the cultured cells demonstrated extremely pleiomorphic cells with large prominent nucleoli. Cell proliferation was determined with a non-radioactive propidium-iodide assay and indicated an in vitro doubling time of approximately 58 hr. Furthermore, the cell line was characterized by cytogenetic analysis, electron microscopy, immunocytochemistry and Northern blotting for HLA and c-myc-mRNA analysis. Cytogenetic analysis revealed numerical abnormalities of chromosome 8 and structural abnormalities of chromosome 6. By electron microscopy, different stages of melanosome development were observed. Immunocytochemical analysis demonstrated expression of the melanoma-associated antigen gp 100. Expression analysis of HLA antigens revealed a very low level of, in particular, the HLA-B locus products, which could be induced by interferon-alpha or -gamma treatment. Likewise, Northern-blot experiments revealed decreased levels of HLA-B mRNA as compared with HLA-A. In addition, high levels of c-myc expression were observed. The phenotypic characteristics of the cultured cells indicate that we have established an uveal melanoma cell line. This now well-characterized uveal melanoma cell line can be used in future studies.