Cytokine-mediated modulation of HLA-class II, ICAM-1, LFA-3 and tumor-associated antigen profile of melanoma cells. Comparison with anti-proliferative activity by rIL1-beta, rTNF-alpha, rIFN-gamma, rIL4 and their combinations

Cell-state dynamics and therapeutic resistance in melanoma from the perspective of MITF and IFNγ pathways

Targeted therapy and immunotherapy have greatly improved the prognosis of patients with metastatic melanoma, but resistance to these therapeutic modalities limits the percentage of patients with long-lasting responses. Accumulating evidence indicates that a persisting subpopulation of melanoma cells contributes to resistance to targeted therapy or immunotherapy, even in patients who initially have a therapeutic response; however, the root mechanism of resistance remains elusive. To address this problem, we propose a new model, in which dynamic fluctuations of protein expression at the single-cell level and longitudinal reshaping of the cellular state at the cell-population level explain the whole process of therapeutic resistance development. Conceptually, we focused on two different pivotal signalling pathways (mediated by microphthalmia-associated transcription factor (MITF) and IFNγ) to construct the evolving trajectories of melanoma and described each of the cell states. Accordingly, the development of therapeutic resistance could be divided into three main phases: early survival of cell populations, reversal of senescence, and the establishment of new homeostatic states and development of irreversible resistance. On the basis of existing data, we propose future directions in both translational research and the design of therapeutic strategies that incorporate this emerging understanding of resistance.

The Role of Cytokines in the Modulation of Cell Surface Antigens of Human Melanoma

A number of different cytokines, including IL-1α. and ß, IL-2, IL-3, IL-4, IL-6, IL-7, IL-8, IFN-α, -ß and γ, TNF-α -ß, and TGF-ß1, can modulate the expression of distinct cell surface antigens of normal and neoplastic cells. Both induction/increase of expression and reduction of expression can be achieved depending on the antigen and on the cytokine. Antigens subjected to the modulating activity of cytokines include distinct families of cell surface structures such as the molecules coded by the major histocompatibility complex (MHC), the superfamily of adhesion receptors that regulate cell-cell and cell-matrix interaction, receptors for cytokines and growth factors and tumor-associated antigens. The modulating activity of cytokines is a consequence of their influence on gene expression, protein synthesis, membrane expression and shedding of antigens from the cell surface. The changes of phenotype due to the action of cytokines can influence the signalling pathways dependent on the expression and function of cell surf ace structures. Therefore, the antigen modulating activity of cytokines can thoroughly affect the biological behavior of normal and neoplastic cells. As described here, most of the modulating effects of cytokines on different cell surface structures and the functional consequences of antigenic modulation can be verified in human malignant melanoma cells.

Staphylococcal superantigens of the enterotoxin gene cluster (egc) for treatment of stage IIIb non-small cell lung cancer with pleural effusion

There has been renewed interest in the superantigens as antitumor agents with the discovery of a group of bacterial superantigens known as the enterotoxin gene cluster (egc staphylococcal enterotoxins [SEs]). This article discusses the mechanisms by which egc SEs induce tumor killing and pleurodesis. The application of SE homolog and nucleic acid compositions as vaccines and for treatment of established tumors is reviewed. Finally, the use of native SEs ex vivo-intratumorally and intravesicularly administered superantigens against established tumors-is described and the interrelation between superantigen therapy and chemoradiotherapy.

Expression of SOCS-1, suppressor of cytokine signalling-1, in human melanoma

Cytokine resistance is a well-established feature of melanoma cell progression and represents also a major obstacle in immunotherapy of patients with metastatic melanoma. To check whether suppressors of cytokine signalling (SOCS) play a role in cytokine resistance and tumor progression of melanoma, we investigated the expression and regulation of SOCS-1, an established negative regulator of interleukin-6 (IL-6) and interferon (IFN) signalling. In vitro SOCS-1 transcripts were detectable by RT-PCR in 8 out of 8 human melanoma cell lines derived from different tumor stages. Normal human melanocytes also expressed SOCS-1 mRNA in the presence or absence of artificial growth factors. Both IL-6 and alpha-IFN induced rapid and transient SOCS-1 mRNA expression in WM35 and WM9 melanoma cells. At the protein level, SOCS-1 was undetectable in normal human melanocytes whereas uniformly expressed in all tested melanoma cell lines. The aberrant SOCS-1 protein expression in melanoma cells was recapitalized in situ as shown by immunohistochemical analysis. SOCS-1 immunoreactivity was closely related to tumor invasion (Clark level), tumor thickness according to Breslow, and stage of the disease. In contrast, melanocytes in normal skin or melanocytic nevi lacked SOCS-1 protein expression. Our findings show that melanoma cells express a member of the SOCS family, SOCS-1, in vitro and in situ. SOCS-1 is a progression marker of human melanoma and may downregulate biological responses by endogenous and/or therapeutically administered cytokines.

Evaluation of gene expression in human lymphocytes activated in the presence of melatonin

The effect of melatonin on the expression of genes previously correlated to T lymphocyte activation (HLA-DRB, thymosin beta 10 (beta-Tim)) and to Lymphokine Activated Killer (LAK) activity (beta-Tim, Tumour Rejection Antigen (TRA 1), nRap 2) was investigated in phytohemagglutinin (PHA)-stimulated human lymphocyte cultures. The aim was to find an enhancing effect of this substance on anti-tumoral immune defences as suggested by studies on tumour progression in mice and clinical immunotherapy trials in humans. mRNA obtained from melatonin-treated and -untreated PHA-stimulated lymphocytes was retrotranscribed and amplified by RT-PCR using primers based on the sequences of the selected genes. The results suggest that melatonin does not increase T and LAK cell responses: in fact, a reduction in the transcription of all the considered genes was observed. These data are correlated with the antiproliferative effect of melatonin observed in in vitro treated lymphocytes.

T-cell-directed cancer vaccines: mechanisms of immune escape and immune tolerance

Recent clinical trials using vaccines directed toward tumour-associated antigens (TA) have shown the increasing capacity of vaccines to cause immunologic responses. In fact, strongly reactive TA-specific cytolytic T-lymphocytes and tumour-infiltrating lymphocytes (TIL) can be identified and expanded ex vivo from patients with metastatic melanoma vaccinated with melanoma-associated antigens. Paradoxically, this strong immunological response does not correlate with clinical tumour regression. Proposed mechanisms responsible for this glaring inconsistency are numerous and varied; systemic immunosuppressive as well as local mechanistic factors are implicated. In this review we will critically evaluate the possible mechanisms that allow tumours to escape immune destruction and be tolerated by the immune system. In addition, strategies that may allow further insight into the biology of tumour rejection are discussed, in the hope of deepening the understanding of this phenomenon and enhancing its therapeutic potential.

IFN-gamma can promote tumor evasion of the immune system in vivo by down-regulating cellular levels of an endogenous tumor antigen

Although IFN-gamma has been generally thought to enhance antitumor immune responses, we found that IFN-gamma can promote tumor escape in the CT26 colon carcinoma by down-regulating the protein expression of an endogenous tumor Ag. gp70, the env product of the endogenous ecotropic murine leukemia virus, has been reported to be the immunodominant Ag of CT26. We show that IFN-gamma down-regulates intracellular and surface levels of gp70 protein resulting in a reduced lysis by CTL, which is restored by pulsing IFN-gamma-treated CT26 with the L(d)-restricted immunodominant AH1 epitope derived from gp70. To investigate the role of CT26 sensitivity to IFN-gamma in vivo, we constructed two variants of CT26, CT26.mugR and CT26.IFN, that are unresponsive to IFN-gamma or express IFN-gamma, respectively. We demonstrate using these variants that tumor responsiveness to IFN-gamma promotes a reduction in tumor immunogenicity in vivo that is correlated with an increased tumor incidence in immune mice. Analysis of the tumors from mice challenged with CT26 or CT26.mugR revealed infiltration of CD8 T cells secreting IFN-gamma. We conclude that IFN-gamma secreted by tumor-infiltrating T cells promotes tumor escape through the down-regulation of the endogenous tumor Ag gp70. These findings have impact on the design of effective antitumor vaccine strategies.

Phase II evaluation of interleukin-4 in patients with non-Hodgkin's lymphoma: a Southwest Oncology Group trial

We performed a phase II, Southwest Oncology Group (SWOG) clinical trial of recombinant human interleukin-4 (rhuIL-4) in patients with previously treated non-Hodgkin's lymphoma (NHL). We studied 18 eligible patients with low-grade and 21 patients with intermediate- or high-grade NHL. All patients had received prior chemotherapy. A protocol amendment after the first four patients reduced the frequency of s.c. rhuIL-4 administration from daily to 3 times per week at 3 microg/kg and limited the number of prior chemotherapy regimens allowed. We documented no complete or partial responses in the low-grade NHL group [0%; 95% confidence interval (CI) 0-19%]. One patient in the intermediate/high-grade NHL group developed a partial response lasting longer than 15 months (5%; 95% CI 0-24%). Median survivals for the low- and intermediate/high-grade NHL groups were 15 and 13 months, respectively. Common toxicities included: arhralgia/myalgia, fatigue/malaise/lethargy, fever, headache, nausea and rigors/chills. Cardiac toxicity, gastrointestinal ulceration and nasal congestion due to rhuIL-4 were not prominent toxicities in our patients. Our previously treated NHL patients tolerated s.c. rhuIL-4 at a dose of 3 microg/kg given 3 times per week, but objective response rarely occurred. Further evaluation of rhuIL-4 in these patient populations does not appear warranted.

Adenovirus-mediated expression of interleukin-12 induces natural killer cell activity and complements adenovirus-directed gp75 treatment of melanoma lung metastases

Based on the knowledge that adenovirus (Ad)-mediated expression of the murine gp75 melanoma antigen (Adgp75) will effectively immunize mice against H2-matched B16 melanoma cells, probably via cell- mediated immune mechanisms, we hypothesized that Ad-mediated delivery of the murine interleukin-12 (IL-12) complementary DNA heterodimer would have independent therapeutic effects on tumor growth, and that the combination of the two vectors would work synergistically to augment the antitumor response. We evaluated the therapeutic effect of each vector alone and in combination for efficacy in C57BL/6 mice with preestablished (2 d) B16 melanoma-derived pulmonary metastases, using the number of lung metastases as the efficacy parameter. Intraperitoneal administration of Adgp75 (10(8) PFU) reduced tumor burden to 45 +/- 7% of controls (P < 0.01), and AdIL12 administration (10(8) PFU, intraperitoneally) reduced the number of metastases to 43 +/- 7% of controls (P < 0.01). The combination of Adgp75 (10(8) PFU, intraperitoneally) and AdIL12 (10(8) PFU, intraperitoneally) provided further protection (15 +/- 3%; P < 0.01 as compared with naive control; P < 0.01 compared with Adgp75 or AdIL12 alone). Mice receiving AdIL12 showed increased natural killer cell (NK cell) function in an in vitro cytotoxicity assay, with a dose- dependent lysis of YAC-1 cells and, to a lesser extent, lysis of B16 cells. To assess the relative contribution of major histocompatibility complex I (MHC I) Dependent and Independent activity in combination therapy with Adgp75 plus AdIL12, we performed adoptive transfer experiments, using splenocytes from mice receiving Adgp75, AdIL12, or Adgp75 + AdIL12, from among which NK cells had been selectively depleted in vitro prior to adoptive transfer. Each group showed significant decreases in tumor burden resembling those with primary treatment. Interestingly, NK-cell depletion from among cells derived from the Adgp75- and AdIL12-treated mice significantly altered the therapeutic response (P < 0.01 compared with the Adgp75 + AdIL12 group), suggesting a significant role of NK-cell-mediated cytolysis in vivo, although there was still a significantly reduced tumor burden (P < 0.01 compared with that of naive controls). Collectively, these data support the concept that the combination of AdIL12 and Adgp75 provides additive effects against pulmonary metastases of B16 melanoma by MHC-independent (NK cell) means as well as MHC-dependent cytotoxic lymphocyte means, suggesting that this therapy may be a useful adjuvant in the treatment of metastatic melanoma.

Expression of ICAM-1 during IFN-alpha-based treatment of metastatic malignant melanoma: relation to tumor-infiltrating mononuclear cells and regressive tumor changes

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in cell to cell interactions. In malignant melanoma, ICAM-1 expression correlates with malignant behavior. We used monoclonal antibodies, anti-ICAM-1, anti-CD4+, anti-CD8+, and anti-CD11c+ to study the effect of interferon-alpha (IFN-alpha) on the expression of ICAM-1 by melanoma cells in regional metastases and its correlation to the occurrence of CD4+, CD8+, and CD11c+ cells close to tumor cells and in the tumor stroma. We also estimated the expression of ICAM-1 and regressive changes in malignant melanoma metastases, correlating the duration of treatment to these effects of IFN-alpha. Twenty-three IFN-alpha-treated and 10 untreated patients with regional metastatic malignant melanoma were studied. The duration of IFN-alpha treatment influenced the expression of ICAM-1. In metastases from patients treated for 1 week only, 1 of 5 showed high expression of ICAM-1 compared with 6 of 11 of those treated for 3 weeks (p = 0.01, chi-square test for trend comparing untreated patients and patients with various durations of IFN-alpha treatment). In IFN-alpha-treated patients with low expression of ICAM-1, none of 7 metastases showed CD4+ cells infiltrating close to tumor cells, in contrast to 6 of 10 metastases expressing high amounts of ICAM-1 (p = 0.03). Similarly, the expression of ICAM-1 was found to correlate with the occurrence of CD8+ cells close to the tumor cells (p = 0.04). We also showed a correlation between ICAM-1 expression and histologic evidence of tumor regression (p = 0.02).

Cytokine sensitivity of metastatic human melanoma cell lines-- simultaneous inhibition of proliferation and enhancement of gelatinase activity

The effect of a panel of cytokines on the proliferation and type IV collagenase production was studied in four melanoma cell lines of different origin, tumorigenicity and metastatic capacity. TGF-b, TNF-a and to a lesser extent, IL-1a exhibited antiproliferative effect on the cell lines, with some lines showing varying degree of resistance. The sensitivity did not correlate directly with the origin or the biological behavior of the tumor lines, suggesting that cytokine resistance of advanced stage melanoma cells may be relative. IL-2, IL-10 and IL-12 displayed little or no effect on proliferation. The effect of cytokines on metalloproteinase production showed a cell line dependent pattern. Interestingly, those cytokines that exhibited the most pronounced antiproliferative activity, also proved most effective in stimulating collagenase secretion, often simultaneously, in the same line. The results indicate that pleiotropic cytokines can have positive and negative effects simultaneously on various steps of tumor progression.

Immunohistochemical analysis of intercellular adhesion molecule-1 expression in human gastric adenoma and adenocarcinoma

In this study, we examined the distribution of intercellular adhesion molecule-1 (ICAM-1) in gastric adenomas and carcinomas immunohistochemically at the light and electron microscopic levels. ICAM-1 was expressed on tumour cells in 12 of 28 gastric carcinomas and in 3 of 11 adenomas but not on most normal gastric epithelial cells. ICAM-1 was localized on luminal sites of neoplastic glands in adenomas and in intestinal-type carcinomas, and rarely on the surface of tumour cells of diffuse carcinomas. Expression of ICAM-1 on the tumour cells was more frequent in intestinal-type than diffuse carcinomas (P < 0.005). At the ultrastructural level, ICAM-1 was present prominently on the apical membrane and weakly on the lateral surface of the tumour cells of the intestinal-type carcinoma and also localized on the perinuclear membrane and the membrane of the endoplasmic reticulum of cancer cells. There was no significant association between ICAM-1 expression and HLA antigen expression or the number of infiltrating lymphocyte subsets. These results may implicate the synthesis of ICAM-1 by gastric cancer cells, but the expression is infrequent and may not be sufficient for host immune surveillance of the tumour cell.

Tolerance to p53 by A2.1-restricted cytotoxic T lymphocytes

Elevated levels of the p53 protein occur in approximately 50% of human malignancies, which makes it an excellent target for a broad-spectrum T cell immunotherapy of cancer. A major barrier to the design of p53-specific immunotherapeutics and vaccines, however, is the possibility that T cells may be tolerant of antigens derived from wild-type p53 due to its low level of expression in normal thymus and lymphohemopoetic cells. The combination of p53 deficient (p53-/-) and p53+/+ HLA-A2.1/Kb transgenic mice was used as a model to explore the possibility that A2.1-restricted cytotoxic T lymphocytes (CTL) are functionally tolerant of self peptides derived from the wild-type p53 tumor suppressor protein. A2.1-restricted CTL specific for a naturally processed p53 self-epitope spanning residues 187-197 were completely aborted in p53+/+ as opposed to p53-/- transgenic mice. In contrast, CTL specific for a second self-epitope spanning residues 261-269 of the murine p53 sequence were detected in both p53-/- and p53+/+ A2.1/Kb transgenic mice. However, the avidity of the CTL effectors obtained from p53+/+ mice was 10-fold lower than that obtained from p53-/- mice, again suggesting elimination of CTL with high avidity for the A2.1-peptide complex. The circumvention of functional tolerance of high avidity CTL may therefore be a necessary prerequisite for optimizing immunotherapy against A2.1-restricted wild-type p53 epitopes in humans.

Identification of Her-2/Neu CTL epitopes using double transgenic mice expressing HLA-A2.1 and human CD.8

The Her-2/neu protooncogene is associated with malignant transformation and aggressive disease. Because of its overexpression in tumor cells and because it has been shown to be immunogenic, this protein represents an excellent target for T-cell immunotherapy. By identifying potential HLA-A2.1-binding peptides from the Her-2/neu sequence, peptides were selected as candidate T-cell epitopes. The immunogenicity of each peptide was evaluated by priming double transgenic mice expressing both the human (hu) CD8 and HLA-A2.1 molecules with synthetic peptides corresponding to these sequences. Because of the lack of interaction between murine CD8 and HLA-A2.1, expression of huCD8 on murine cells facilitates recognition of HLA molecules on human tumor cell lines. This led to the identification of two peptides that elicit an A2-restricted CTL response, one of which has not been previously identified. Both peptide-specific CTL populations were able to specifically lyse A2.1 and Her-2/neu expressing human tumor cells originating from a variety of tissues, demonstrating the utility of this murine model in identifying peptides presented by human cells. However, several Her-2/neu peptides previously reported to be immunogenic for human CTL were found not to be immunogenic in transgenic mice. The basis for these discrepancies is discussed.

Melanoma and stroma: an interaction of biological and prognostic importance

Stromal relationships are crucial to metastatic spread of solid malignancies. Some aspects of this stroma interaction are obviously associated with particular morphological features, which may carry prognostic significance. In cutaneous melanoma, level of invasion, arrangement of cells (horizontal or vertical growth phase), neovascularization, vessel invasion, architecture of the border, and inflammatory infiltrate have been examined. Expression of adhesion molecules, signalling factors, cytoskeletal components, extracellular matrix molecules and matrix-degrading enzymes have been assessed by immunohistology and in situ hybridization. Besides providing prognostic information, a thorough evaluation of stromal relationships may help to increase our knowledge about factors mediating the growth and metastatic spread of malignancies.

Increased levels of serum intercellular adhesion molecule-1 (ICAM-1) in patients with non-small cell lung cancer

Serum concentrations of soluble ICAM-1 were measured by an enzyme-linked immunosorbent assay in 80 patients with non-small cell lung cancer (NSCLC). The mean serum concentration of soluble ICAM-1 in 80 patients with NSCLC was 472.8 +/- 370.8 ng ml-1 (range 75.6-3177.4 ng ml-1), whereas it was 196.8 +/- 54.6 ng ml-1 (range 128.1-276.4 ng ml-1) in 10 healthy controls. Sixty of 80 patients with NSCLC (75.0%) showed elevated concentrations (more than 306 ng ml-1, mean+2 SD in controls). The differences in mean serum concentration and positive rate between control subjects and NSCLC patients were significant (P = 0.0001). Serum ICAM-1 concentrations showed a significantly positive correlation with primary tumour size (maximum diameter) (P = 0.0209). Although the difference was not significant, the overall survival of patients with low serum ICAM-1 concentrations (< 306 ng ml-1) tended to be longer than that of patients with high concentrations (> or = 306 ng ml-1). These results suggest that serum ICAM-1 may be useful for serological diagnosis, monitoring of tumour volume or quantity in patients with NSCLC.

Tumor necrosis factor-alpha expression in human primary malignant malanoma and it relationship to tumor infiltration by CD3+ cells

Optimal conditions for immunohistochemical staining of tumor necrosis factor-alpha (TNF-alpha) in paraffin-embedded tissue sections were established to investigate TNF-alpha expression in human primary malignant melanomas. Seventeen malignant melanomas of the nodular (NMM) and superficially spreading (SSM) subtypes were analyzed. Twelve of these were TNF-alpha+, while 5 did not stain for the cytokine. To evaluate how TNF-alpha expression affected the immune response to the tumors, infiltration by CD3+ and mac387+ cells was investigated in NMM. TNF-alpha expression seemed to selectively affect the capability of T cells to infiltrate the tumors since TNF-alpha+ tumors were found to have significantly lower levels of infiltrating CD3+ cells, while there was no difference in numbers of mac387+ cells. These results demonstrate that TNF-alpha is variably expressed in primary malignant melanoma in vivo and that the T-cell response to TNF-alpha-expression NMM is inhibited.

Expression of type A and B tumor necrosis factor (TNF) receptors on melanoma cells can be regulated by dbc-AMP and IFN gamma

Local administration of high-dose r-TNF alpha with IFN gamma in the limbs of melanoma patients has proved to be a very promising treatment. To understand the role played by the effect of TNF on melanoma cells in tumor destruction, we have investigated the expression of TNF-receptors in melanoma cells using monoclonal antibodies specific for the type-A (75-kDa) and the type-B (55-kDa) TNF receptors. Flow cytometric analysis of cultured melanoma cells indicated the presence of both types of receptor. Quantificative differences in the relative levels of receptors were observed for different cells lines, although the type-B receptor was generally more strongly expressed. Similar results were obtained by immunohistochemistry on cryosections from tumor samples. Positive staining of variable intensity was observed for the type-B TNF-receptor in a high percentage of tumor cells. The type-A TNF-receptor was also detected, but with a weaker staining. The total TNF-binding activity of cultured melanoma cells, as measured by binding of 125I-labeled TNF alpha, was up-regulated between 2- and 4-fold by incubation of cells with activators of protein kinase A or IFN gamma. Treatment of cultured melanoma cells with dbc-AMP resulted in a selective induction of type-A TNF-receptors, without affecting the type-B receptor level. In contrast, IFN gamma was able to induce either type of receptor in a cell-line-dependent fashion. Addition of TNF alpha to melanoma cells induced the activation of the nuclear transcription factor kappa B, as measured in an electrophoretic mobility shift assay, thus indicating the biological significance of the TNF-receptors on these cells.

Heavy-metal modulation of the human intercellular adhesion molecule (ICAM-1) gene expression

The intercellular adhesion molecule 1 (ICAM-1) can be induced on many different cell types by a set of various modulators (IL1 beta, TNF, LPS, IFN-gamma), which are released during the inflammatory process. We have investigated the possibility that other factors, related to the stress and biophysical perturbations of the inflammatory response, may also modulate ICAM-1. Here, we report that heavy metals, in particular zinc, can enhance the expression of the ICAM-1 gene on cells actively involved at different levels during inflammation. Kinetic studies of ICAM-1 gene expression shows a maximum level of induction 4 h after treatment with metals, followed by a rapid decrease to basal levels within 12 h. The effect on enhanced gene expression is mostly due to a rapid increase of the transcriptional rate as shown by nuclear run-on experiments. In B lymphoblastoid cells, but not in fibroblasts, the increase in RNA expression seems significantly greater that the subsequent increase in protein expression, suggesting that a further point of post-transcriptional regulation of ICAM-1 occurs and may be linked to the cellular specificity. may be linked to the cellular specificity.

Production of cytokines by human melanoma cells and melanocytes

Experimental animal models have shown that various cytokines, depending of their specific properties, may support growth and metastasis of tumor cells or even lead to tumor rejection. The analysis of expression of cytokine genes by melanoma cell lines indicated that melanoma cells constitutively produce both autostimulatory and inhibitory cytokines. Using reverse transcriptase polymerase chain reaction analysis, simultaneous expression of several cytokines, including interleukin-1 beta (IL-1 beta), IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor, by melanoma cells was found. The same cytokine transcripts were detected in melanocytes, suggesting that cells of the melanocytic lineage express a specific pattern of cytokines in vitro. All these cytokines are known to be able to stimulate effector cells of the host. Additionally, production of mRNA for IL-10, a cytokine with potential immunosuppressive properties, was detected in melanoma cells and melanocytes. These and other cytokines are likely to be involved in the immune response to cancer and at this time it is unknown what the net effects of multiple cytokines are on the outcome of the host response to tumor.

Growth control of melanoma cells and melanocytes by cytokines

Aberrant proliferation of tumor cells characterizes cancer growth. Investigations of cellular growth control mechanisms have contributed to our understanding of carcinogenesis and to the identification of compounds with specific antitumor activity. Many cytokines have been found to act on melanoma tumors, either produced by the tumor cells themselves or by infiltrating host cells. Purified cytokines allowed direct comparison of the growth response between normal human melanocytes and malignant melanoma cells. The present paper summarizes results of a series of our own experiments not yet published and data from a review of the recent literature. Proliferation of normal human melanocytes is enhanced by several cytokines, including basic fibroblast growth factor (bFGF), melanoma growth stimulatory activity (MGSA), hepatocyte growth factor (HGF), and mast cell growth factor (MGF). Melanoma cells are additionally stimulated by epidermal growth factor (EGF)/transforming growth factor alpha (TGF-alpha) and nerve growth factor (NGF). Tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta 1 (TGF-beta 1), and interleukin (IL)-6 are all potent inhibitors of melanocyte growth, but they are less effective on melanoma cells or even stimulate their growth. Interferon (IFN)-alpha and IFN-gamma inhibited proliferation of melanoma cells but not of melanocytes, whereas IFN-beta showed antiproliferative effects in both cell types. These findings suggest an alteration in growth control mechanisms during melanocyte transformation and possibly play a role in melanoma pathogenesis.

Local immune response to tumor invasion in esophageal squamous cell carcinoma. The expression of human leukocyte antigen-DR and lymphocyte infiltration

BACKGROUND

The purpose of this study was to investigate the local immune response to tumor invasion in esophageal squamous cell carcinoma by using an immunohistochemical examination of the expression of human leukocyte antigen- (HLA) DR and lymphocyte infiltration.

METHODS

The paraffin embedded sections from 108 patients with esophageal squamous cell carcinoma were studied immunohistochemically, using the streptavidin biotin peroxidase method with monoclonal antibody (HLA-DR, T-cell, and B-cell) in the 68 noninvasive sites of cancer (intraepithelial carcinoma) and the 108 invasive sites of cancer.

RESULTS

The expression of HLA-DR antigen was detected in 49 of 108 cases (45%) of esophageal cancer. The expression of this antigen was more predominant in intraepithelial carcinoma than at the invasive sites of cancer (60% versus 22%, P < 0.01). Among the 40 cases with positive staining for HLA-DR antigen in intraepithelial carcinoma, negative staining of the invasion portion was shown in 27 (67.5%) cases. On the other hand, in the 28 cases with negative staining in intraepithelial carcinoma, 27 cases (96.4%) were also negative at the invasive sites. T-cell infiltration was significantly recognized at the area of HLA-DR antigen expression at the sites of both intraepithelial carcinoma and tumor invasion. However, no significant relationship was observed between the HLA-DR antigen expression and long term survival at this time.

CONCLUSIONS

These results suggest that the local immune response to the HLA-DR may prevent tumor invasion, whereas the negative expression of HLA-DR antigen is a significant factor facilitating tumor invasion in esophageal squamous cell carcinoma.

Regulation of ICAM-1 (CD54) expression in human breast cancer cell lines by interleukin 6 and fibroblast-derived factors

Four human breast cancer cell lines (T47D, ZR-75-1, MCF7D and HS578T) were examined for the effects of cytokines on expression of cell surface antigens. Interferon (IFN)gamma up-regulated the expression of ICAM-I (CD54) in all the cell lines and coordinately up-regulated both CD54 and CD40 expression in T47D. Tumour necrosis factor (TNF)alpha, interleukin (IL)1 alpha, IL1 beta and IL6 also up-regulated the expression of CD54 in all the cell lines but CD40 was unaffected. Levels of expression of CD11a, CD18, CD49b, CD58 and CD71 were unaltered by these cytokines. Conditioned medium (CM) generated from human fibroblasts, and in particular from foetal cells, was highly effective in up-regulating expression of ICAM-1 but not of CD40 in the breast cancer cell lines. ICAM-1 induction correlated with IL6 bioactivity in these CMs. Combinations of IL6 with other cytokines, such as IL1, resulted in further increases in ICAM-1 expression. Our observations suggest that IL6 is involved in intercellular signalling between mesenchyme and breast cancer epithelium.

Interleukin-6 (IL-6) production and cell growth of cultured human ameningiomas:-interactions with interleukin-1 beta (IL-1 beta) and interleukin-4 (IL-4) in vitro

We examined the production of interleukin (IL)-6 by human meningioma cells in vitro, and the effects of IL-1 beta and IL-4 on IL-6 production and meningioma cell growth. The histological classification of the tumours studied included transitional, syncytial, fibroblastic and atypical. All 10 meningiomas studied produced IL-6 (range 0.22-7.6 ng/ml/10(6) cells/24 h). Separate addition of IL-1 beta or IL-4 to cultures increased IL-6 production up to ten fold, and two to three fold, respectively. Growth studies with IL-6 indicated that this cytokine significantly increased terminal cell density at a concentration greater than 1 ng/ml in 60% of the meningioma cultures studied. IL-1 beta caused a significant decrease in the terminal cell density in 25% of the meningioma cultures studied whereas IL-4 had a tendency to significantly inhibit growth in 16.6% of the cultures. These data suggest that IL-6 production by meningiomas can be modified by other cytokines and secondly, that IL-6, IL-1 beta and IL-4 can modify growth in vitro and may act as autocrine factors in vivo. By further determining the cytokine profiles within meningiomas and their effects, a better understanding of meningioma growth characteristics may be obtained.

Interferon-gamma increases cellular calcium ion concentration and inositol 1,4,5-trisphosphate formation in human renal carcinoma cells: relation to ICAM-1 antigen expression

In the present study, we investigated the effect of interferon-gamma (IFN-gamma) on cellular calcium ion concentration [Ca2+]i and inositol 1,4,5-trisphosphate (Ins 1,4,5-P3) formation in the human renal carcinoma cell line CaKi-1. We also examined the possible role of a Ca(2+)-dependent mechanism during IFN-gamma-induced intercellular adhesion molecule 1 (ICAM-1) antigen expression. IFN-gamma caused a rapid concentration-dependent rise in [Ca2+]i, which was partly inhibited by diltiazem, a calcium channel blocker, TMB-8, an inhibitor of intracellular calcium redistribution, and in calcium-free medium. IFN-gamma caused a fourfold increase in Ins 1,4,5-P3 formation. The induction of ICAM-1 antigen expression was synergistically enhanced by 4-bromocalcium ionophore A23187. Finally, the calcium antagonists diltiazem. TMB-8 and EGTA, as well as two potent inhibitors of Ca(2+)-dependent kinases, calmidazolium (R24571) and W7, had no or only a minor inhibitory effect on IFN-gamma induction. Our data suggest that IFN-gamma increases [Ca2+]i in CaKi-1 cells by stimulating influx of Ca2+ and release of Ca2+ from intracellular stores, probably via Ins 1,4,5-P3 formation. IFN-gamma signal transduction in our model may not be limited to an increase in [Ca2+]i and Ins 1,4,5-P3, since IFN-gamma-induced ICAM-1 antigen expression was abrogated to a minor degree by calcium antagonists and not coupled to Ins 1,4,5-P3 formation.

Comparison of the effects of tumour necrosis factor alpha stimulation and phorbol ester treatment on the immunocytochemical staining of intercellular adhesion molecule 1 in human renal carcinoma cell cultures

Incubation of the human renal carcinoma cell line CaKi-1 with tumour necrosis factor alpha (TNF alpha) or the phorbol ester phorbol-12-myristate 13 acetate (PMA) strongly enhanced the immunocytochemical staining of the intercellular adhesion molecule ICAM-1, in a non-linear manner. Since PMA is capable of activating Ca2+/phospholipid-dependent protein kinase C (PKC), we investigated the role of this kinase during TNF alpha signal transduction. Calcium ionophore A23187 significantly enhanced PMA, but not TNF alpha-induced ICAM-1 staining. The PKC inhibitors H7, staurosporine and sphingosine abrogated the action of PMA, while TNF alpha was unaffected. Simultaneous incubation with TNF alpha and PMA resulted in maximal ICAM-1 staining significantly above values obtained when cultures were treated with either agent alone. Finally, chronic PMA treatment with subsequent TNF alpha stimulation enhanced ICAM-1 staining above values from cultures where TNF alpha was omitted. Our findings suggest that the immunocytochemical staining of ICAM-1 in CaKi-1 cells can be induced by TNF alpha through mainly PKC-independent mechanisms or by PMA through PKC-dependent mechanisms. The two agents may work synergistically in this respect.

Lymphotoxin gene expression by melanocytes and melanoma cell lines and persistence of unspliced mRNA

Human melanoma cell lines express many different cytokines [1], including lymphotoxin (LT), the production of which has been considered to be restricted to cells of the lymphocytic lineage in response to cell activation. LT expression by melanomas is constitutive and characterized by the presence of two mRNAs. In the present paper we report an analysis of the origin of the two LT-specific transcripts in four human melanoma cell lines at different stages of progression and in four melanocytic cell lines. Reverse transcription-polymerase chain reaction (RT-PCR) performed with primers lying in the first and fourth exons and hybridization with intron probes showed a spliced and a full-unspliced LT mRNA. This pattern was also displayed by one of four melanocyte cell lines. Western blot analysis indicated that LT RNA is properly translated to a 23-25 kDa protein and immunocytochemistry showed its localization within the cytoplasm and on the cell membrane.

Interferon-gamma-induced increased sensitivity of HER2/neu-overexpressing tumor cells to lymphokine-activated killer cell lysis: importance of ICAM-1 in binding and post-binding events

Treatment of HER2/neu-overexpressing target cells with interferon gamma (IFN gamma) (200-2000 U/ml for 3 days) markedly enhances their sensitivity to lymphokine-activated killer (LAK) cell lysis. Increased sensitivity is associated with an up-regulation of intercellular adhesion molecule ICAM-1 determinants and a down-regulation of HER2/neu expression. In the present study, we show that exposure to another cytokine, tumor necrosis factor alpha (200 U/ml for 3 days), also decreased HER2/neu expression but had no effect on LAK cell lysis and ICAM-1 expression. This suggests that down-regulation of oncogene expression is not sufficient by itself to induce an enhanced sensitivity to LAK cell lysis. IFN-induced enhanced lysis was associated with an increased binding between effectors and targets, and antibodies to ICAM-1 as well as its counter-receptor LFA-1, blocked the increased binding and lysis. Treatment with IFN gamma still significantly enhanced lysis even when concanavalin A was added to the assay to induce maximal binding, indicating that a post-binding effect also participated in enhanced cytotoxicity. These post-binding alterations, were also sensitive to blocking with anti-ICAM-1 and anti-LFA-1 antibodies. Treatment with IFN also sensitized targets to lysis by T cells in the presence of lectin but had no effect on the relative resistance of HER2+ cells to lysis mediated by perforin or TNF. Together these data demonstrate the importance of ICAM-1 determinants in binding and post-binding events in the IFN-induced increased lysis of HER2/neu+ targets.

Interferon gamma and tumour necrosis factor alpha induce a synergistic antiproliferative response in human Ewing's sarcoma cells in vitro

Three human cell lines derived from Ewing's sarcoma (RM-82, VH-64, and WE-68) were investigated to establish the influence of recombinant human interferon gamma (rhIFN gamma) and tumour necrosis factor alpha (rhTNF alpha) on cell proliferation and survival and to characterize IFN gamma and TNF alpha receptor expression. Incorporation of [3H]thymidine into cells was inhibited by rhIFN gamma after 24 h of incubation. Half-maximal inhibition was observed with 10-80 U/ml rhIFN gamma. A maximal effect (50%-70% inhibition of cell proliferation) was achieved by treatment of cells with 250 U/ml rhIFN gamma. The influence of rhTNF alpha on proliferation was found to differ among cell lines and varied with the concentration and the duration of exposure of cells to this cytokine. In WE-68 and VH-64 cells [3H]thymidine incorporation was not affected by rhTNF alpha up to 2000 U/ml after 96 h of incubation, whereas in RM-82 cells the incorporation was inhibited by 35% after 48 h of incubation with 100 U/ml rhTNF alpha. However, all cell lines showed a synergistic antiproliferative response to the combination of rhIFN gamma and rhTNF alpha after 24 h of incubation. The human recombinant cytokines interleukin(IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-6 and granulocyte/macrophage-colony-stimulating factor, tested alone and in combination with rhIFN gamma and rhTNF alpha, had no influence on cell proliferation. Binding studies in the cell lines with 125I-rhIFN gamma revealed a dissociation constant (Kd) of 160-306 pM and approximately 8000-13,500 receptors/cell. Binding experiments with 125I-rhTNF alpha indicated 430-1250 receptors/cell with Kd ranging from 13 pM to 162 pM. These data indicate that, among various cytokines, only IFN and TNF alpha are capable of potently reducing Ewing's sarcoma cell growth in vitro. Our data suggest that IFN alone or in combination with TNF alpha may be useful in the design of novel strategies in Ewing's sarcoma therapy.

Human melanoma cells express a functional interleukin-2 receptor

Flow cytometric analysis reveals that 5 human melanoma cell lines (M14, IGR3, ME1477, JUSO, GLL19) express both alpha and beta chain of the interleukin 2 receptor (IL-2R alpha and IL-2R beta). These chains are able to specifically bind IL-2 and to form high-affinity heterodimers (IL-2R alpha beta). Analysis of poly A+ RNAs by Northern blot reveals the presence of typical transcripts for both the IL-2R alpha gene (3.6 kb) and the IL-2R beta gene (4 kb). Reverse transcription/polymerase chain reaction analysis allowed transcripts for the IL2R gamma (p64) gene to be detected in 3 of these melanoma cell lines (M14, IGR3, ME 1477). Incubation with human recombinant IL-2 modifies in IL-2R alpha+beta+gamma+ (M14) the expression of several surface molecules: down-regulation of ICAM-1, HLA class I and HLA-DR and up-regulation of CD44. IL-2 is also active on IL-2 alpha+beta+gamma- cell lines since it decreases ICAM-1 and HLA class-II expression at the surface of JUSO cells. Down-regulation of ICAM-1, whose expression in melanoma cells is a marker of tumor progression, is detectable within 3 hr in M14 cells and is maximal after 48 hr incubation, at IL-2 concentrations corresponding to the high-affinity heterodimers. This feature is specific since it is partially inhibited by MAbs directed against the IL-2 binding site of the IL-2R alpha (MAR93, 10T14) and IL-2R beta (MiK beta 1, TU27) chains. Our data support the notion of a direct effect of IL-2 on human melanoma cells. Modulation of the expression of surface molecules which is important for the interaction with immunocompetent cells or for tumor progression, could have a role to play during in vivo IL-2 treatment of human melanomas.

Lesion-specific activation of cloned human tumor-infiltrating lymphocytes by autologous tumor cells: induction of proliferation and cytokine production

To investigate the mechanisms by which tumor-infiltrating lymphocytes exert their antitumor effects, tumor-specific tumor-infiltrating lymphocyte clones, as well as autologous tumor cell lines from primary and secondary tumors of two patients during the course of melanoma progression were established. Enrichment for tumor-infiltrating lymphocytes expressing CD25, as well as low concentrations of interleukin-2 (30 IU/ml) in the culture medium, led to a preferential outgrowth of cells that express the high-affinity interleukin-2 receptor. All of these expressed CD2, CD3, CD11, and CD25. Coculture of tumor-infiltrating lymphocyte clones with irradiated, autologous tumor cells induced an up to 480% greater proliferative responses than recombinant interleukin-2 alone. Approximately 60% of the tumor-infiltrating lymphocyte clones showed cytotoxicity against the relevant tumor in a 4-h 51Cr-release assay. When tested in an 18-h 51Cr-release assay, the number of tumor-infiltrating lymphocyte clones exhibiting cytotoxicity against the relevant tumor increased to over 85%. In response to autologous tumor cells, nine of 15 clones secreted interferon-gamma, tumor necrosis factor-alpha, or both. Cytokine production was not restricted to either CD4+ or CD8+ T cells because both CD4+ and CD8+ tumor-infiltrating lymphocyte clones secreted cytokines. Tumor-infiltrating lymphocyte tumor interaction appears to be lesion specific because induction of proliferation and cytokine production, as well as susceptibility to cytolysis, was found not only restricted to the autologous system, but also to the specific lesion. The pattern of tumor-infiltrating lymphocyte tumor interaction specificity indicates a possible loss of antigens expressed on the tumor during disease progression.

Role of protein kinase C during interferon-gamma- and phorbol ester-stimulated immunocytochemical expression of ICAM-1 in human renal carcinoma cells

Incubation of the human renal carcinoma cell line CaKi-1 with interferon-gamma (IFN-gamma) or the phorbol ester, phorbol-12-myristate 13-acetate (PMA) strongly stimulated the immunocytochemical expression of the intercellular adhesion molecule-1 (ICAM-1) in a dose-dependent manner. Since PMA is capable of activating the Ca2+/phospholipid-dependent protein kinase C (PKC), we investigated the role of this kinase during IFN-gamma signal transduction. Calcium ionophore A23187 significantly enhanced IFN-gamma- and PMA-induced ICAM-1 staining. While staurosporine, H7 and sphingosine, three known PKC inhibitors, blocked the PMA effect, only staurosporine abrogated the action of IFN-gamma. Finally, 24 h of PMA pretreatment with subsequent IFN-gamma stimulation enhanced ICAM-1 staining above values from cultures where IFN-gamma was omitted. This occurred despite the fact that 24 h of PMA pretreatment abolished the effect of IFN-gamma on PKC activation, as determined by acetylated myelin basic protein 4-14 phosphorylation. In conclusion, these results suggest that additional events other than PKC activation are required for complete regulation of ICAM-1 antigen by IFN-gamma in the whole cell population. Hence, other Ca(2+)-dependent signalling pathway(s) mediated by IFN-gamma receptors must act. Further studies are needed to elucidate these specific pathway(s) activated during IFN-gamma stimulation in our model.

Differential expression and release of LFA-3 and ICAM-1 in human melanoma cell lines

We examined 10 different melanoma cell lines for cellular expression and release of ICAM-1 (CD54) and LFA-3 (CD58) and the influence of cytokines, including IFN alpha, IFN gamma and TNF alpha. Cellular ICAM-1 expression and density varies considerably between the melanoma cell lines. While IFN alpha has no effect on cellular ICAM-1 (cICAM-1) expression, IFN gamma and to a lesser extent TNF alpha can effectively up-regulate cICAM-1. Soluble ICAM-1 (sICAM-1) is detected in the supernatants of all lines tested, release of sICAM-1 correlates with cellular expression. LFA-3 does not much differ in its expression level on melanoma lines, and cytokines have little or no effect on its expression. Soluble LFA-3 is released by only 6 out of 10 lines. Its release can effectively be inhibited by IFN gamma in all lines and by TNF alpha in one, while IFN alpha has no effect. These data show that expression and release of LFA-3 and ICAM-1 differ between melanoma cell lines. This may be of importance for the interaction of melanoma cells with immune effector cells in vivo.

Intercellular adhesion molecule-1 on cultured human melanoma cells: influence of cytokines

Adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) and its counter-receptor, lymphocyte function associated antigen-1 (LFA-1), play very important roles in immune responses. In this study, the effects of cytokines on cultured human melanoma cells (MMG2) were examined, especially focussing on the expression of ICAM-1 on MMG2 and lymphocyte adhesion to MMG2. Both the expression of ICAM-1 and HLA-DR on MMG2 increased after treatment with IFN-gamma. ICAM-1 expression began to increase earlier than HLA-DR expression. TNF-alpha and IL-1 beta also increased the expression of ICAM-1 on MMG2. However, these cytokines did not increase the expression of HLA-DR. IFN-gamma had a dose dependent effect on lymphocyte adhesion to MMG2. Pretreatment of IFN-gamma treated MMG2 with 84H10 (anti-ICAM-1 antibody) or pretreatment of lymphocytes with either SPV-L7 (anti-LFA-1 alpha antibody) or IOT10 (anti-LFA-1 beta antibody) inhibited the lymphocyte adhesion to MMG2. These results suggest that ICAM-1 molecules induced on melanoma cells by IFN-gamma can interact with LFA-1 molecules on lymphocytes.

Cytokine regulation of cell-to-cell interactions in lymphokine-activated killer cell cytotoxicity in vitro

The permanent pancreas carcinoma cell line, PCI-24, was developed in order to analyse cytokine regulation on pancreas carcinoma and lymphokine-activated killer (LAK) cell interaction. PCI cells expressed ICAM-1 and HLA-ABC, but not HLA-DR antigens. PCI cells showed augmented ICAM-1 and HLA-ABC expression when incubated with interferon gamma (IFN gamma) and tumour necrosis factor alpha. A similar but weak augmentary effect on the HLA-ABC and ICAM-1 surface expression was seen with interleukin-1 beta treatment. Natural attachment of LAK to PCI cells was augmented by recombinant IFN gamma in close association with ICAM-1 up-regulation on PCI cells. In addition, natural attachment was significantly inhibited by anti-LFA-1 and anti-ICAM-1 antibody treatments. Cytotoxicity of the LAK cells against PCI cells was also significantly inhibited with the same treatment. Thus, the attachment of LAK cells to PCI cells through LFA-1/ICAM-1 molecules appeared to be essential for the cytotoxicity for PCI cells. Pretreatment of PCI cells, but not of LAK cells, with IFN gamma or other cytokines resulted in a decrease of susceptibility for LAK cell cytotoxicity. The decreased susceptibility inversely correlated with HLA-ABC expression on the PCI cells. The collective evidence indicates that, although LAK cell attachment to pancreas carcinoma cells through the LFA-1/ICAM-1 molecule is augmented by IFN gamma, IFN gamma treatment of pancreas carcinoma cells reduces LAK cell cytotoxicity possibly through an increase in HLA-ABC or a regulation of molecules closely associated to HLA-ABC expression.

Tumour-infiltrating lymphocytes in primary melanoma: functional consequences of differential IL-2 receptor expression

Tumour-infiltrating lymphocytes (TIL) have been isolated from early primary melanoma (Clark level III) and expanded in vitro using culture conditions with low concentrations of IL-2 (50 U/ml). Immediately after isolation TIL consisted of mainly CD3+ T cells, and the portion of CD56+ natural killer (NK) cells was below 20%. Fresh TIL cultures could be distinguished by CD25 expression since some contained up to 33%, others less than 5% CD25+ cells. These showed differences in subsequent development during in vitro expansion. CD25-expressing cultures remained stable in their phenotype, whereas the second TIL type showed major changes: CD3 (ca 70-30%) expression decrease, CD25 (ca 5-35%) and CD56 (ca 15-55%) expression increase. The TIL type, which remained dominated by CD3+ T cells, killed autologous tumour cells efficiently (51Cr-release greater than 30% at a E/T ratio of 20:1), which could be blocked by MoAbs against MHC class I molecules. In contrast, the other TIL type exhibited weak cytotoxicity (less than 17% 51Cr-release at an E/T ratio of 20:1) against the autologous tumour. Therefore, the expression of CD25 on freshly isolated TIL is a good marker for tumour specificity of in vitro expanded TIL.

Expression of intercellular adhesion molecule 1 (ICAM-1) during the development of invasion and/or metastasis of gastric carcinoma

In this study, using two-color flow-cytometric analysis, we examined the expression of histocompatibility locus antigens (HLA) classes I and II, and intercellular adhesion molecule 1 (ICAM-1) in 10 cases of normal gastric mucosa, 13 cases of primary carcinoma on the stomach, 16 cases of metastatic carcinoma from malignant ascites in patients with gastric carcinoma and 14 samples of their cultured carcinoma cells. Compared with normal gastric mucosa, HLA class I were highly expressed in a considerable number of tumor cells in each experimental group. The expression of HLA class II tended to reduce in the order of normal gastric mucosa, primary gastric carcinoma and peritoneal-effusion-associated carcinoma. Altogether, 85.7% of cases of cultured tumor cells showed abrogation and loss of HLA class II. The ICAM-1 molecule was not detected on normal gastric epithelial cells. In few cases, carcinoma cells from large volumes of tumor located in the stomach showed detectable amounts of ICAM-1. On the other hand, all of the metastatic carcinoma cells from peritoneal effusions showed a high level of expression of the ICAM-1 molecule. The expression of ICAM-1 on adenocarcinoma cells was maintained and/or augmented by in vitro cultivation with tumor-infiltrating lymphocytes (TIL). Furthermore, two-color fluorescence-activated cell sorting analysis of TIL revealed that significant correlation was observed between the expression of ICAM-1 and the degree of TIL, composed mainly of CD3+ T cells including CD8+CD11b-, CD8+CD28+, CD8+S6F1+ and CD4+Leu8+, and CD57+CD16- and CD57+CD16+ NK cells, and HLA-DR+LeuM3+ macrophages.

Interleukin-4 receptor and epidermal growth factor receptor expression in colorectal cancer

Interleukin-4 receptor (IL-4R) and Epidermal Growth Factor receptor (EGFR) were assessed as factors associated with adenoma-carcinoma progression in colorectal cancer and tumour invasion. A monoclonal antibody (MR6) was applied to detect IL-4R in: metaplastic polyps (five cases), adenomas (15 cases), and carcinomas (44 adenocarcinomas and one squamous cell). Positive labelling was obtained in all polyps, adenomas and in 40/45 carcinomas. Normal colonic mucosa of these patients, as well as macrophages and lymphocytes infiltrating the tumour stroma, were also positively labelled with MR6. Four out of five poorly differentiated adenocarcinomas did not show IL-4 receptor expression. No significant correlation was found with tumour size, lymph node stage and IL-4 receptor expression. On the above specimens a parallel detection of epidermal growth factor receptors (EGFR) by a monoclonal antibody (EGFR 1) was carried out. Expression of EGFR was found in 14/20 polyps and in 22/45 carcinomas. All but one of the EGFR positive malignant tumours showed coexpression of IL-4 receptor. Lymph node involvement by tumour cells was detected in 25 out of 45 patients. Eighteen of these 25 cases were positive with EGFR1.

Cell retargeting by bispecific monoclonal antibodies. Evidence of bypass of intratumor susceptibility to cell lysis in human melanoma

Intratumor heterogeneity for susceptibility to cytotoxic T lymphocytes (CTL)-mediated lysis represents a major obstacle to cancer adoptive immunotherapy. To overcome the heterogeneity observed in terms of susceptibility of target cells to cell-mediated lysis, in this study we used two purified bispecific monoclonal antibodies (bsmAbs) that recognize molecules expressed by cytotoxic effector cells (CD3 and IgG Fc receptorial molecules), as well as one high molecular weight melanoma-associated antigen (HMW-MAA). The ability of these reagents to enhance or induce a relevant in vitro cytotoxic activity by a CTL clone (CTL 49) isolated from PBL of a melanoma patient was tested on a large panel of autologous and allogeneic melanoma cell lines and clones. Functional studies revealed that the CTL 49 clone lysed all the HMW-MAA+ tumor lines in the presence of bsmAbs and that these reagents affected the target lysis in a cooperative fashion. The effectiveness of bsmAbs in overcoming the heterogeneous susceptibility of human melanoma cells to cell-mediated lysis may find practical implications in cancer adoptive immunotherapy.

The inhibitory effects of interferon gamma on the growth of bladder cancer cells

The inhibitory effect of interferon-gamma on the growth of three human bladder cancer cell lines, RT4, RT112 and MGH-U1, representing tumour grades 1, 2 and 3 respectively, was studied. The effects of 10, 100 and 1000 Uml.-1 of interferon-gamma on cell numbers and thymidine incorporation were measured at 24 hour intervals up to a maximum of seven days. Morphological appearances were also studied. Each line was susceptible to the growth inhibitory effects of interferon-gamma and this was both dose and time dependent. The effects of interferon-gamma, on the RT4 and RT112 cells were apparent from 24 hours, and were both cytostatic and cytotoxic in nature, whereas the effects on MGH-U1 cells were seen from 48 hours onwards and were only cytostatic. Cytological changes occurred in all three cell lines, being most pronounced in RT112. The growth of bladder cancer cells was inhibited by interferon-gamma, and in this study high grade tumour cells were least sensitive.

Differential cytostatic activity of monocyte-derived cytokines against human melanoma cells

We investigated the capacity of 3 major cytokines secreted by activated monocytes, IL-1 beta, TNF alpha and IL-6, to inhibit growth of melanoma tumor cells. Using neutralizing antibodies against IL-1 beta, TNF alpha and IL-6, we observed that the cytostatic activity against A375 melanoma cells is largely due to the presence of IL-6 in culture supernatants of monocytes stimulated with LPS. A375 cells appeared to be extremely sensitive to monocyte-derived cytokines, since in addition to rIL-6 also rIL-1 beta and rTNF alpha displayed cytostatic activity against A375 cells. We observed additive or synergistic cytostatic effects upon use of combinations of these cytokines. When 7 other melanoma cell lines and short-term melanoma cultures were tested and compared with A375, a major difference in their sensitivity to monocyte-derived cytokines were observed. Although 7 out of 8 melanoma cell lines were sensitive to culture supernatants of monocytes stimulated with LPS, significant differences were found when recombinant cytokines were used. The widely used A375 was the only melanoma cell line sensitive to rIL-1 beta, rTNF alpha and rIL-6. The growth of none of the other 7 melanoma cell cultures was significantly affected by rIL-1 beta. Seven out of 8 melanoma cell cultures were sensitive to rTNF alpha and 3 out of 8 to rIL-6. The results of our study indicate that the sensitivity of melanoma cell cultures for different monocyte-derived cytokines is highly variable, and that it is questionable whether the A375 melanoma cell line, sensitive to rIL-1 beta, rTNF alpha and rIL-6, is representative for melanoma.

Role of interferon gamma and tumour necrosis factor alpha in monocyte-mediated cytostasis and cytotoxicity against a human histiocytic lymphoma cell line

In view of cellular adoptive immunotherapy we have studied monocyte-mediated cytostasis and cytotoxicity against U 937 cells, a human histiocytic lymphoma cell line. Highly purified human monocytes and monocyte-derived macrophages were activated with interferon gamma (IFN) or tumour necrosis factor alpha (TNF) to antileukemic immune effector cells. Antileukemic activity of human monocytes was dependent on monocyte differentiation into macrophages and on a dose- and time-dependent activation with IFN or TNF. Maximum cytostasis of 97.0 +/- 0.7% (mean +/- SEM) (conventional [3H]dT uptake assay) and 81.9 +/- 5.3% cytotoxicity (modified MTT assay) of U 937 cells was obtained by monocytes activated with 100 U/ml IFN for at least 24 h at an effector-to-target-cell ratio of 10. U 937 cells premodified with IFN showed an increase in susceptibility to monocyte-mediated cytotoxicity. U 937 cells premodified with TNF were almost resistant to monocyte-mediated cytotoxicity while activated monocytes maintained their cytotoxic potential. These data show that IFN and TNF are potent activators of monocyte-mediated cytotoxicity. Furthermore, IFN and TNF might be involved in the regulation of the susceptibility of leukemic cells to lysis by interactions with monocytes or macrophages.

Ectopic parasellar pituitary adenoma with subarachnoid seeding

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