Differential expression of CD28 and CD94/NKG2 on T cells with identical TCR beta variable regions in primary melanoma and sentinel lymph node

NK cell tolerance is maintained by the interaction of killer inhibitory receptors with self MHC class I gene products. A subset of T cells also express killer inhibitory receptors, but the functional significance of this is unclear. Here we demonstrate that the expression of the C-lectin-like killer inhibitory receptor CD94 / NKG2 on T cells depends on the state of differentiation during the immune response to solid tumors. To this end we identified clonally expanded T cells which were present both in the sentinel lymph node of primary melanoma, as well as in the tumor itself. In situ characterization of such T cell clonotypes revealed that within the early stages of T cell activation, i. e. priming in the lymph node, T cells did not express CD94 / NKG2 whereas the same T cell clones expressed high levels of CD94 / NKG2 having reached the effector state at the tumor site. Moreover, while the phenotype of these T cell clones was CD28high in the lymph node only CD28low or CD28- T cells were found within the tumor. Double staining for CD94 and CD28 conformed that CD94 / NKG2-expressing cells were preferentially CD28-. Thus, T cells may down-regulate CD28 and up-regulate NK receptors as consequence of prolonged activation for cytolytic effector function. It is likely that NK receptors are involved in peripheral regulatory mechanisms avoiding overwhelming immune responses and immunopathology, particularly in situations of long-lasting immune activation.

Expression and activation of matrix metalloproteinase-2 (MMP-2) and its co-localization with membrane-type 1 matrix metalloproteinase (MT1-MMP) correlate with melanoma progression

Matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs) play an important role in cancer cell invasion and metastasis. Recently, it was shown that the presence of activated MMP-2 correlates with melanoma progression in vitro. This activation involves coordinated expression of MMP-2, membrane-type 1 MMP (MT1-MMP), and TIMP-2. To investigate the expression profile of these enzymes in human melanoma, this study used tumour specimens obtained from both a human melanoma xenograft model, consisting of eight melanoma cell lines with different metastatic capacity in nude mice, and 60 fresh human cutaneous melanocytic lesions comprising all stages of melanocytic tumour progression. MT1-MMP and TIMP-2 mRNA and protein were present in all cell lines. Cell surface expression level of MT1-MMP, as determined by flow cytometry, was similar on all cell lines. In addition, western blot analysis revealed that both inactive and active MT1-MMP protein was expressed by all cell lines. MMP-2 mRNA and the pro-enzyme form of MMP-2 were expressed by all cell lines. Remarkably, the presence of functionally active MMP-2 was restricted to the most aggressive cell lines MV3 and BLM. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of RNA isolated from subcutaneous xenografts revealed MT1-MMP and TIMP-2 mRNA expression in all lesions, whereas MMP-2 mRNA could be detected only in xenografts derived from the highly metastatic cell lines 1F6m, MV3, and BLM. Furthermore, immunohistochemistry demonstrated a marked increase of MMP-2 and MT1-MMP in MV3 and BLM xenografts, whereas TIMP-2 expression showed no evident correlation with metastatic capacity. In human cutaneous melanocytic lesions, MMP-2, MT1-MMP, and TIMP-2 mRNA were detectable by RT-PCR in all lesions. Expression of MMP-2 protein was not detectable, either in common and atypical naevi, or in melanoma in situ by immunohistochemistry. In these lesions, heterogeneous expression of MT1-MMP and TIMP-2 was present in melanocytic cells. In contrast, a large number of MMP-2 and MT1-MMP-positive tumour cells were observed in primary melanomas and melanoma metastases. Double staining experiments and immunohistochemistry on serial sections from the same lesions demonstrated that all tumour cells expressing MMP-2 also expressed MT1-MMP and TIMP-2. Finally, zymography of melanoma metastases revealed that MMP-2 was present in its functionally active form. This study demonstrates that expression of MT1-MMP and TIMP-2 and activation of MMP-2 are correlated with tumour progression both in the xenograft model and in human melanocytic lesions, strongly suggesting that these factors are required for melanoma invasion and metastasis formation.

Coexpression of integrin alpha(v)beta3 and matrix metalloproteinase-2 (MMP-2) coincides with MMP-2 activation: correlation with melanoma progression

Tumor cell invasion and metastasis formation depend on both adhesive and proteolytic mechanisms. Previous studies have shown that expression of matrix metalloproteinase-2 and integrin alphavbeta3 correlate with melanoma progression. Recently, direct binding of matrix metalloproteinase-2 to alpha(v)beta3 was implicated in presenting activated matrix metalloproteinase-2 on the cell surface of invasive cells. In this study we investigated this, using the highly metastatic, alpha(v)beta3-negative melanoma cell lines MV3 and BLM, their beta3-transfected alpha(v)beta3 expressing counterparts, xenografts derived from these cell lines, and fresh human cutaneous melanoma lesions comprising all stages of melanoma progression. Expression and activation status of matrix metalloproteinase-2 were studied by reverse transcription-polymerase chain reaction, immunohistochemistry, western blotting, and zymographic analysis, respectively. Matrix metalloproteinase-2 protein expression in vitro was similar in both alpha(v)beta3-negative and alpha(v)beta3-positive cell lines Remarkable differences, however, exist in the localization of inactive and active matrix metalloproteinase-2. Soluble active matrix metalloproteinase-2 was detectable only in the conditioned medium of alpha(v)beta3-negative cell lines and undetectable in the alpha(v)beta3-positive cell lines. Conversely, active matrix metalloproteinase-2 was present exclusively on the cell surface of the alpha(v)beta3 expressing transfectants. Western blot analysis of other components that are involved in matrix metalloproteinase-2 activation showed that processing of proMT1-matrix metalloproteinase to the activated form was enhanced in beta3 transfectants, whereas secretion of tissue inhibitor of metalloproteinase-2 was decreased. In vivo, the presence of functionally active matrix metalloproteinase-2 was significantly higher in xenografts derived from the alpha(v)beta3 expressing MV3 and BLM cell lines. In human cutaneous melanoma lesions, neither matrix metalloproteinase-2 nor integrin alpha(v)beta3 is detectable in melanoma in situ as determined by immunohistochemistry. In contrast, the number of matrix metalloproteinase-2-positive and alphavbeta3-positive tumor cells was clearly increased in primary melanomas, and melanoma metastases. Double staining experiments and confocal laser microscopy demonstrated that the percentage of cells coexpressing matrix metalloproteinase-2 and alpha(v)beta3 increased in advanced primary melanomas and melanoma metastases. In addition, zymography showed that functionally active matrix metalloproteinase-2 was frequently present in melanoma metastases. In these lesions a high proportion of matrix metalloproteinase-2- and alphavbeta3-double-positive melanoma cells were detectable. Our study demonstrates that the presence of activated matrix metalloproteinase-2 correlates with expression of alpha(v)beta3 in human melanoma cells both in vitro and in vivo, and also in fresh human melanoma lesions. These findings strongly suggest that co-ordinated expression of both factors may be required for melanoma cell invasion and metastasis formation.

Sequential interferon-alpha2b, interleukin-2 and fotemustine for patients with metastatic melanoma

The aim of this study was the evaluation of both the antitumour activity and toxicity of an immunochemotherapeutic regimen consisting of interferon-alpha2b and interleukin-2 in combination with fotemustine for patients with metastatic melanoma. To improve the penetration of fotemustine into the brain, it was given immediately after immunotherapy, when the blood-brain barrier is still disturbed. Of the 19 patients treated, three complete remissions (CRs) and one partial remission (PR) were induced, giving an objective response rate of 21% (95% confidence interval 6-46%). The durations of the CRs were 9, 19 and 44 months; the PR lasted for 59+ months. The overall survival times for the patients with CR were 21, 25 and 70+ months, and 59+ months for the PR. For nine patients (47%, 95% confidence interval 24-71%) disease was stabilized for a median period of 8 months (range 2-18 months), resulting in a median survival of 18 months (range 10-41+ months). No haematological toxicity of World Health Organization grade 3 or more was observed and in general toxicity was low. In summary, this immunochemotherapy regimen led to long-term survival in occasional patients, and about half of the patients achieved stable disease, with prolonged treatment- and progression-free survival compared with nonresponding patients. The occurrence of brain metastases, however, was not prevented, and in fact was the site of recurrence in those patients achieving a CR. Due to its low toxicity, this protocol can be applied at a community hospital level.

Classical chemotherapy for metastatic melanoma

Despite a major effort in clinical research scrutinizing various treatment regimens for patients suffering from metastatic melanoma the prognosis for these patients still remains poor. The treatment options tested have ranged from monochemotherapy, polychemotherapeutic approaches including highly toxic regimens requiring autologous bone marrow rescue, immuno-modulatory therapies, e.g. defined cytokines such as interferon-alpha and interleukin-2 as well as vaccination therapy with dendritic cells or genetically modified tumour cells, and bio-chemotherapy. Although immuno-modulatory approaches are currently regarded as the most promising, to date no improved overall survival has been achieved by any of these measures especially if tested in large multicentre trials. The focus of this review will be on classical chemotherapy with emphasis on both cutaneous and uveal melanoma.

Tumor infiltrating lymphocytes in melanoma comprise high numbers of T-cell clonotypes that are lost during in vitro culture

Melanoma is generally accepted as being an antigenic tumor capable of eliciting T-cell responses that, however, in most cases are inadequate to control tumor growth. Tumor-infiltrating lymphocytes (TIL) in melanoma lesions comprise clonotypic T cells, indicating the in situ recognition of melanoma-associated peptide epitopes. Cultured TIL have been studied in order to unveil characteristics of TIL and the interactions of TIL and melanoma cells. Whether in vitro cultured TIL mirrors the in situ situation has, however, been questioned. In the present study we have taken advantage of T-cell receptor clonotype mapping methodology to conduct a full and detailed analysis of the T-cell clonotypes in melanoma lesions and in corresponding lines of TIL established in vitro. All melanoma lesions and the corresponding TIL cultures comprised high numbers of T-cell clonotypes, typically in the range of 40 to more than 60. The subsequent comparison of T-cell clonotypes present in the original lesions and in the corresponding T-cell lines established in vitro demonstrated that a very limited number of the T-cell clonotypes established in vitro are identical to the T-cell clonotypes expanded in situ. These results demonstrate that in situ T-cell clonotypes in melanoma are not readily expanded in vitro and that the majority of T-cell clonotypes present in cultured TIL are not present in situ.

Expression and activation of matrix metalloproteinase-2 (MMP-2) and its co-localization with membrane-type 1 matrix metalloproteinase (MT1-MMP) correlate with melanoma progression

Matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs) play an important role in cancer cell invasion and metastasis. Recently, it was shown that the presence of activated MMP-2 correlates with melanoma progression in vitro. This activation involves coordinated expression of MMP-2, membrane-type 1 MMP (MT1-MMP), and TIMP-2. To investigate the expression profile of these enzymes in human melanoma, this study used tumour specimens obtained from both a human melanoma xenograft model, consisting of eight melanoma cell lines with different metastatic capacity in nude mice, and 60 fresh human cutaneous melanocytic lesions comprising all stages of melanocytic tumour progression. MT1-MMP and TIMP-2 mRNA and protein were present in all cell lines. Cell surface expression level of MT1-MMP, as determined by flow cytometry, was similar on all cell lines. In addition, western blot analysis revealed that both inactive and active MT1-MMP protein was expressed by all cell lines. MMP-2 mRNA and the pro-enzyme form of MMP-2 were expressed by all cell lines. Remarkably, the presence of functionally active MMP-2 was restricted to the most aggressive cell lines MV3 and BLM. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of RNA isolated from subcutaneous xenografts revealed MT1-MMP and TIMP-2 mRNA expression in all lesions, whereas MMP-2 mRNA could be detected only in xenografts derived from the highly metastatic cell lines 1F6m, MV3, and BLM. Furthermore, immunohistochemistry demonstrated a marked increase of MMP-2 and MT1-MMP in MV3 and BLM xenografts, whereas TIMP-2 expression showed no evident correlation with metastatic capacity. In human cutaneous melanocytic lesions, MMP-2, MT1-MMP, and TIMP-2 mRNA were detectable by RT-PCR in all lesions. Expression of MMP-2 protein was not detectable, either in common and atypical naevi, or in melanoma in situ by immunohistochemistry. In these lesions, heterogeneous expression of MT1-MMP and TIMP-2 was present in melanocytic cells. In contrast, a large number of MMP-2 and MT1-MMP-positive tumour cells were observed in primary melanomas and melanoma metastases. Double staining experiments and immunohistochemistry on serial sections from the same lesions demonstrated that all tumour cells expressing MMP-2 also expressed MT1-MMP and TIMP-2. Finally, zymography of melanoma metastases revealed that MMP-2 was present in its functionally active form. This study demonstrates that expression of MT1-MMP and TIMP-2 and activation of MMP-2 are correlated with tumour progression both in the xenograft model and in human melanocytic lesions, strongly suggesting that these factors are required for melanoma invasion and metastasis formation.

CD40-ligated dendritic cells effectively expand melanoma-specific CD8+ CTLs and CD4+ IFN-gamma-producing T cells from tumor-infiltrating lymphocytes

Professional APC, notably dendritic cells (DC), are necessary for stimulation and expansion of naive T cells. By means of murine models, the interaction between CD40 on DC and its ligand CD154 has been recognized as an important element for conditioning of DC to prime and expand CTL. We translated these findings into the human system, scrutinizing the ability of DC to initiate clonal expansion of single T cells. DC generated under completely autologous conditions from peripheral blood monocytes were cocultured at a rate of 0.3 cell/well with melanoma-infiltrating T cells; this procedure guaranteed that either a CD4+ or a CD8+ cell interacted with the DC, thus avoiding the contact of more than one T cell to the DC. In the absence of further stimulation, this cloning protocol yielded almost exclusively CD4+ T cell clones that predominantly exhibited a Th2 phenotype. However, cross-linking of CD40 on DC resulted in the induction of IFN-gamma-producing Th1 CD4+ T cell clones. In addition, CD40-activated DC were capable of expanding CD8+ CTL clones. The ratio of CD4 to CD8 T cell clones corresponded to the ratio present in the initial tumor-infiltrating lymphocyte preparation. The CTL clones efficiently lysed autologous tumor cells whereas autologous fibroblasts or MHC-mismatched melanoma cells were not killed. Our findings support the critical role of CD40/CD154 interactions for the induction of cellular immune responses.

Expression of CD94/NKG2 subtypes on tumor-infiltrating lymphocytes in primary and metastatic melanoma

Natural killer receptors are expressed both on natural killer populations and subpopulations of T cells, mainly alpha/beta TCR+CD8+ T cells. We have characterized the expression of the C-type lectin natural killer receptor CD94/NKG2 on tumor-infiltrating lymphocytes in primary and metastatic melanoma lesions. By immunohistochemistry, 5-10% of the tumor-infiltrating lymphocytes, both in primary and metastatic lesions, expressed CD94. More than 95% of these CD94+ cells coexpressed CD8 and the percentage of CD94 expression within the CD8+ cell population ranged from 5 to 20% with a higher expression in metastatic lesions. CD94/NKG2 exists both in an inhibitory and an activating form; thus, it was necessary to determine whether the inhibitory CD94/NKG2-A/B, the activating CD94/NKG2-C/E, or both were expressed on tumor-infiltrating lymphocytes. Reverse transcription-polymerase chain reaction using specific primers for NKG2-A/B and C/E mRNA revealed the presence of NKG2-C/E in all primary and metastatic lesions. In contrast, the inhibitory NKG2-A/B was only present in 50% of primary tumors whereas 80% of tumor-infiltrating lymphocytes in metastatic lesions expressed these transcripts. In healthy humans, the mean number of inhibitory natural killer receptors is higher than that of activating receptors, but the opposite was true for tumor-infiltrating lymphocytes in melanoma. The reversal of the ratio of inhibitory to activating natural killer receptors among tumor-infiltrating lymphocytes suggests a regulated event due to either specific factors within the tumor microenvironment, preferential homing of T cell subsets, or certain stages of T cell activation.

Newcastle disease virus infection induces B7-1/B7-2-independent T-cell costimulatory activity in human melanoma cells

Viral oncolysates of Newcastle disease virus (NDV) have been widely used for the treatment of malignant melanoma. Apparently, this nononcogenic and apathogenic paramyxovirus can alter the immunogenicity of tumor cells. To determine the influence of NDV infection on a tumor-specific T-cell response on a functional level, we used autologous primary melanoma cells infected with the NDV-strain Ulster. Therefore, melanoma cells and tumor-infiltrating lymphocytes were prepared from a freshly resected tumor, and tumor-infiltrating lymphocytes were subjected to limited dilution cloning. Proliferation assays of the T-helper cell clone sTS3 (CD4+) showed that the T-cell clone was rendered nonreactive against its autologous major histocompatibility complex II+, B7-1/B7-2- melanoma SMS, even remaining unresponsive to subsequent stimulation by interleukin-2. NDV infection of the SMS melanoma cell line not only completely restored the proliferative response of sTS3 to SMS, comparable with stimulation by cross-linking of anti-CD3/anti-CD28 monoclonal antibodies, but also inhibited the induction of anergy. Electrophoretic mobility shift assays of sTS3 cell lysates revealed the induction of the CD28-responsive complex by coincubation with NDV-infected melanoma cells. Because the induction of this complex of nuclear proteins shows specificity for the activation of the CD28 pathway but functional B7-1/B7-2 expression was not detectable on SMS melanoma cells at any timepoint, we propose the induction of a costimulatory factor different from B7 by NDV viral proteins.

Accumulation of identical T cells in melanoma and vitiligo-like leukoderma

The cloning of genes encoding melanoma antigens has opened new possibilities for the treatment of patients with cancer; however, most tumor rejection antigens recognized by tumor infiltrating lymphocytes are the products of genes that are also expressed by normal melanocytes. Hence, a large set of antigenic determinants of the self have not induced self-tolerance and these peptide determinants furnish target structures for immune responses directed against tumors. The notion that the immunotherapeutic targets involved in cancer regression comprise normal differentiation antigens is stressed by the association between vitiligo-like leukoderma, due to destruction of normal melanocytes, and melanoma regression, due to destruction of cancer cells. Nevertheless, this is the first report to demonstrate by means of a new technique based on reverse transcription polymerase chain reaction and denaturing gradient gel electrophoresis, the presence of clonally expanded T cells with identical BV regions in areas of destruction of both normal and neoplastic cells.

In situ T cells in melanoma

During the past decade new insights have been gained into the role of T lymphocytes in the host's immune response to cancer in general and to melanoma in particular. Several melanoma-associated antigens (MAA) recognized by T cells have been characterized, and a number of HLA class I- and class II-restricted peptides have been identified. These antigens can be divided into three different groups: tumor-associated testis-specific antigens, melanocyte differentiation antigens, and mutated or aberrantly expressed antigens. These proteins give rise to several antigenic peptides. The number of known melanoma-associated peptides that can induce killing by cytotoxic T-lymphocytes (CTL) exceeds 30 and is still increasing. In line with these findings, clinical data indicate that the immune system is essential in the control of tumor growth. A brisk infiltration of lymphocytes is associated with a favorable prognosis, and complete or partial regression of primary melanoma occurs quite frequently. Furthermore, immunomodulatory therapies have accomplished complete or partial tumor regression in a number of patients. However, the immune response is in most cases inadequate to control tumor growth as tumor progression often occurs. Hence, the coexistence of a cellular immune response in melanoma lesions, demonstrated by the presence of clonally expanded T cells, remains a major paradox of tumor immunology. In the present paper we review current knowledge regarding tumor infiltrating lymphocytes (TIL) in melanoma and discuss possible mechanisms of escape from immune surveillance.

Expression of constitutive nitric oxide synthase in rat and human gastrointestinal tract

The aim of this study was to determine the expression of constitutive NO synthases (ecNOS and bNOS) at the protein level in rat and human gastrointestinal tract. We established a quantitative Western blotting method for detection and quantification of ecNOS and bNOS in both species. Human gastric fundus was further analyzed by immunohistochemistry. EcNOS expression at the protein level could be quantified in different organs of the rat gastrointestinal tract and in human gastric mucosal biopsies. Immunohistochemistry of gastric fundus revealed that immunoreactivity for ecNOS was localized mainly in the endothelium of small vessels. In rats, expression of bNOS at the protein level was highest in esophagus. By means of immunohistochemistry of human gastric fundus, immunoreactivity was detected mainly in the plexus of Auerbach. We conclude that isoforms of constitutive nitric oxide synthase can be identified and quantified at the protein level both in rat and human gastrointestinal tract. The presence of bNOS in nerve tissue supports previous observations that NO serves as a transmitter in non-adrenergic, non-cholinergic nerves in human esophagus and stomach. The observation that ecNOS has been found mainly in endothelial cells suggests the involvement of NO in the regulation of mucosal blood flow.

In situ T cell responses against melanoma comprise high numbers of locally expanded T cell clonotypes

It is well established that melanoma cells express Ags that are recognized by autologous T cells in vitro. Tumor-infiltrating lymphocytes in situ comprise clonotypic T cells, suggesting that their expansion is driven by Ag stimulation. Still, little is known about the detailed characteristics of the in situ T cell response. In the present study, we scrutinized this response by analyzing multiple metastatic lesions for the presence of clonotypic T cells. This approach was chosen to distinguish whether the clonal T cell expansion occurs as a systemic or localized phenomenon. TCR clonotype mapping of six s.c. metastases from two patients revealed the presence of multiple (from 40 to >60) clonotypic T cells in all lesions. Clonotypic T cells were present in TCR beta-variable regions expressed both at high and low levels. Comparison of the T cell clonotypes present in different lesions from individual patients demonstrated that, in general, clonotypes were exclusively detected in a single lesion. Hence, anti-melanoma T cell responses are much more heterogeneous than previously anticipated and accommodate a predominance of strictly localized T cell clonotypes.

Predominant expression of Fas (CD95) ligand in metastatic melanoma revealed by longitudinal analysis

The expression of Fas ligand has recently been proposed as a novel tumor escape mechanism for melanoma. To establish the characteristics of Fas ligand expression during the course of melanoma progression we performed a longitudinal study analyzing primary tumors as well as subsequently evolving metastases. In primary melanoma Fas ligand was expressed in two of 20 lesions; this expression was weak and restricted to few parts of the tumors. The Fas ligand positive primary melanomas were rather thick, i.e., 8.5 and 3.8 mm, versus a median of 2.4 mm of the remaining tumors. In contrast, for metastatic melanoma Fas ligand expression was present in six of 11 cases investigated. The metastases of primary tumors displaying Fas ligand maintained its expression. As Fas ligand positive melanoma cells are capable of inducing apoptosis in susceptible cells, e.g., Fas positive tumor infiltrating lymphocytes, we tested for the presence of apoptotic cells in situ by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. This analysis revealed that apoptotic cells were present within the Fas ligand positive tumors. The number of apoptotic cells, however, never exceeded 5% of the total cells. Thus, Fas ligand mediated apoptosis does not seem to be a major immune escape mechanism for melanoma but its expression correlates with the stage of melanoma.

Differential expression of transforming growth factor beta 1 and interleukin 10 in progressing and regressing areas of primary melanoma

The coexistence of tumor specific immunity with a progressing tumor remains a major paradox of tumor immunology. This enigma is most evident in partially regressing melanomas, where efficient eradication of tumor cells is closely linked to uncontrolled tumor growth. Mechanisms involved in this differential susceptibility of tumor cells to the host immune response may include altered production of immunosuppressive cytokines, i.e., transforming growth factor (TGF) beta or interleukin (IL) 10. Since only limited amounts of tissue samples are available from primary tumors, a semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was established which allowed to estimate the amount of cytokine mRNA expressed in a small number of melanoma cells segregated by indirect immunomagnetic isolation. Thereby, we determined the expression of TGF-beta 1 and IL-10 mRNA in melanoma cells obtained from regressing and progressing areas of 9 primary tumors. TGF-beta 1 mRNA could be detected in all undiluted samples from progressing areas and in 7 samples from regression zones. Titration of the sample revealed that in 6 cases TGF-beta 1 mRNA could be detected at a significant higher titer in progressing than in regressing areas. IL-10 mRNA was present in 8 samples obtained from progressing and in 7 samples from regressing tumor areas. In 6 tumors IL-10 mRNA was detectable at a higher titer in the progression zones. Specificity of the PCR amplification was confirmed with a series of restriction enzyme digestions of the resulting PCR product. Based on these findings the hypothesis that immunosuppressive cytokines, such as TGF-beta 1 or IL-10, represent important factors for the melanoma cells to escape immune surveillance is supported.

Expression of endothelial cell-derived nitric oxide synthase (eNOS) is increased during gastric adaptation to chronic aspirin intake in humans

BACKGROUND

Gastric adaptation to aspirin is well-documented. However, the mechanisms underlying the reduction of aspirin-induced mucosal damage despite continued ingestion of the drug remain poorly understood.

METHODS

Eight healthy volunteers who received aspirin 1 g b.d. for 14 days were compared with eight placebo-dosed controls. Gastroscopy with mucosal biopsy was performed, and gastric mucosal blood flow was measured before and following 3, 7 and 14 days of aspirin treatment. At the same time points, tissue concentration and the content of prostaglandin E2 in the gastric juice were determined and expression of endothelial cell-derived nitric oxide synthase (eNOS) in mucosal biopsies was measured using Western blot analysis.

RESULTS

Aspirin-induced mucosal damage that reached a maximum on day 3, declining significantly by day 14. Concomitantly, mucosal blood flow significantly increased on day 3 and returned to initial values on day 14. Aspirin intake led to a significant decrease in prostaglandin E2 concentration in the gastric mucosa and in gastric juice during the whole period of aspirin consumption. eNOS expression started to increase on day 7 in oxyntic mucosa and on day 3 in antral mucosa, reaching its highest values at the end of the consumption of aspirin.

CONCLUSIONS

The human gastric mucosa adapts to prolonged aspirin intake, and this is accompanied by an increase in mucosal blood flow and reduced prostaglandin synthesis. Increase of mucosal eNOS expression might compensate for reduced prostaglandin synthesis and be responsible for gastric adaptation to chronic aspirin intake in humans.

Immunocytokines: a promising approach to cancer immunotherapy

Recombinant antibody-cytokine fusion proteins are immunocytokines that achieve high cytokine concentrations in the tumor microenvironment and thereby effectively stimulate cellular immune responses against malignancies. The activation and expansion of immune effector cells, such as CD8+ T lymphocytes, by interleukin-2 immunocytokines resulted in the eradication of established pulmonary and hepatic metastases of murine melanoma and colorectal carcinoma in syngeneic mouse models. These immunocytokines were equally effective in eliminating established bone marrow and liver metastases of murine neuroblastoma by activating natural killer cells. The effective eradication of metastases by immunocytokines resulted in significant prolongation in life span of mice over that of controls receiving equivalent mixtures of antibody and interleukin-2, which failed to reduce the growth of disseminated metastases. Proof of concept was established, indicating that immunocytokine-induced activation and expansion of immune effector cells in the tumor microenvironment can effectively eradicate established tumor metastases. This promising new approach to cancer immunotherapy may lead to clinical applications that improve treatment of cancer patients with minimal residual disease in an adjuvant setting.

[Immunochemotherapy of metastatic uveal melanoma with interferon alfa-2b, interleukin-2 and fotemustine. Case reports and review of the literature]

In spite of their tumor's origin in the uveal tract, many patients suffering from advanced uveal melanoma are admitted to dermatological oncology units. Most patients with metastases from uveal melanoma receive treatments that were established for stage IV cutaneous melanoma. However, both the biology as well as the metastastic behaviour of this tumor is different from cutaneous melanoma. Lymphatic metastases do not occur, and hematogeneous metastases usually occur later and predominantly involve the liver. The prognosis is very bad ranging from 2 to 5 months. We describe three patients with advanced uveal melanoma who received immunochemotherapy containing interferon-alpha 2b, interleukin-2, and fotemustine. This therapy induced a partial response of more than 49 months duration in one patient, whereas for the remaining patients the disease progression could be stabilized for eight and 16 months, respectively. This therapeutic success is reflected by a prolonged survival of 14,43+, and 59+ months.

Activation of preexisting T cell clones by targeted interleukin 2 therapy

The induction of an immunological antitumor response capable of eradicating metastatic tumors is the ultimate goal of immunotherapy. We have recently shown that this can be achieved by interleukin 2 (IL-2) therapy directed to the tumor microenvironment by a recombinant antibody-IL-2 fusion protein. It is not known, however, whether this curative treatment is associated with a predominance of T cells carrying specific T cell receptor variable beta regions (TCRBV) or the presence of clonally expanded T cells. To address this question, we have used a quantitative reverse transcriptase-coupled PCR method to analyze the TCRBV region repertoire in tumor-infiltrating lymphocytes of treated and untreated animals. As controls the TCRBV region repertoire was analyzed in blood and skin from disease-free animals. The results indicate an overexpression of TCRBV5 in the tumors of all treated mice and an additional overexpression of individual regions in each tumor. Direct sequencing of these TCRBV regions did not reveal any evidence of clonal expansions. However, since clonal expansions could exist as subpopulations in highly expressed regions, not detectable by direct sequencing, a denaturing gradient gel electrophoresis assay was used for clonal analysis of TCRBV PCR products. Denaturing gradient gel electrophoresis analysis of selected TCRBV regions revealed the presence of clonotypic T cells in tumors from both treated and untreated animals. These data indicate that targeted IL-2 therapy in this model does not induce clonal T cell responses de novo, rather it acts as an activator for an already existing population of clonotypic T cells.