HLA-DR histocompatibility leukocyte antigens permit cultured human melanoma cells from early but not advanced disease to stimulate autologous lymphocytes

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Tumor-specific MHC-II expression drives a unique pattern of resistance to immunotherapy via LAG-3/FCRL6 engagement

Immunotherapies targeting the PD-1 pathway produce durable responses in many cancers, but the tumor-intrinsic factors governing response and resistance are largely unknown. MHC-II expression on tumor cells can predict response to anti-PD-1 therapy. We therefore sought to determine how MHC-II expression by tumor cells promotes PD-1 dependency. Using transcriptional profiling of anti-PD-1-treated patients, we identified unique patterns of immune activation in MHC-II+ tumors. In patients and preclinical models, MHC-II+ tumors recruited CD4+ T cells and developed dependency on PD-1 as well as Lag-3 (an MHC-II inhibitory receptor), which was upregulated in MHC-II+ tumors at acquired resistance to anti-PD-1. Finally, we identify enhanced expression of FCRL6, another MHC-II receptor expressed on NK and T cells, in the microenvironment of MHC-II+ tumors. We ascribe this to what we believe to be a novel inhibitory function of FCRL6 engagement, identifying it as an immunotherapy target. These data suggest a MHC-II-mediated context-dependent mechanism of adaptive resistance to PD-1-targeting immunotherapy.

Tumor-specific MHC-II expression drives a unique pattern of resistance to immunotherapy via LAG-3/FCRL6 engagement

Immunotherapies targeting the PD-1 pathway produce durable responses in many cancers, but the tumor-intrinsic factors governing response and resistance are largely unknown. MHC-II expression on tumor cells can predict response to anti-PD-1 therapy. We therefore sought to determine how MHC-II expression by tumor cells promotes PD-1 dependency. Using transcriptional profiling of anti-PD-1-treated patients, we identified unique patterns of immune activation in MHC-II+ tumors. In patients and preclinical models, MHC-II+ tumors recruited CD4+ T cells and developed dependency on PD-1 as well as Lag-3 (an MHC-II inhibitory receptor), which was upregulated in MHC-II+ tumors at acquired resistance to anti-PD-1. Finally, we identify enhanced expression of FCRL6, another MHC-II receptor expressed on NK and T cells, in the microenvironment of MHC-II+ tumors. We ascribe this to what we believe to be a novel inhibitory function of FCRL6 engagement, identifying it as an immunotherapy target. These data suggest a MHC-II-mediated context-dependent mechanism of adaptive resistance to PD-1-targeting immunotherapy.

Turning tumour cells into antigen presenting cells: The next step to improve cancer immunotherapy?

Downregulation/loss of the antigen presentation is a major immune escape mechanism in cancer. It allows tumour cells to become 'invisible' and avoid immune attack by antitumour T cells. In tumour harbouring properties of professional antigen presenting cells (i.e. tumour B cells in lymphoma), downregulation/loss of the antigen presentation may also prevent direct priming of naïve T cells by tumour cells. Here, we review treatments that may induce/restore antigen presentation by the tumour cells. These treatments may increase the generation of antitumour T cells and/or their capacity to recognise and eliminate tumour cells. By forcing tumour cells to present their antigens, these treatments may sensitise patients to T cell-based immunotherapies, including checkpoint inhibitors.

Prediction of Outcome in Diffuse Large Cell Lymphoma by the Major Histocompatibility Complex Class II (HLA-DR, DP, DQ) and Class I (HLA-A, B, C) Phenotype

Ninety-nine consecutive diffuse large cell lymphoma (DLCL) patients were studied by immunohistochemistry to determine whether clinical outcome was predicted by major histocompatibility complex (MHC) antigen phenotypic expression. Statistically significantly shorter disease free survival (p = 0.005), but not overall survival (p = 0.47), was observed when patient lymphomas failed to express class I MHC antigens. We also observed significantly reduced survival of class II MHC HLA-DP negative patients (p = 0.038). This extends our previous finding of poor outcome with absent class II MHC HLA-DR in DLCL(1) to other MHC antigens and demonstrates that the phenomenon of defective class II antigen expression comprises 16% of these DLCL patients. Known clinical parameters predictive of prognosis were equally distributed between phenotypic groups. These findings indicate that aberrancy of immune phenotype in DLCL is critical to patient outcome and we speculate that loss of MHC expression may confound host immunosurveillance and tumor containment.

Tumour-infiltrating lymphocytes in melanoma prognosis and cancer immunotherapy

The field of systemic cancer therapy for metastatic disease has entered an exciting era with the advent of novel immunomodulatory strategies targeting immune checkpoints. At the heart of these promising efforts are the tumour-infiltrating lymphocytes (TILs). As the reports demonstrating efficacy of modulating TIL effector function in patients with advanced stage cancer continue to accrue, it has become essential to better understand TIL immunobiology in order to further improve clinical outcome. In addition to providing an overview of the current immunotherapies available for metastatic melanoma, this review will briefly introduce the history and classification of TILs. Moreover, we will dissect the multifaceted roles of TILs in tumour-specific immunity and melanoma immune escape. The significance of TILs in melanoma prognosis and cancer immunotherapy will also be discussed, with a particular focus on their potential utility as biomarkers of patient response. The goal of personalised medicine appears to be in realistic sight, as new immunomodulatory techniques and technological innovations continue to advance the field of cancer immunotherapy. In light of recent studies highlighting the possible utility of TILs in determining therapeutic outcome, further characterisation of TIL phenotype and function has the potential to help translate individualised care into current medical practice.

Tumor-infiltrating lymphocytes and their significance in melanoma prognosis

The role of the tumor-infiltrating lymphocyte (TIL) and its relationship to prognosis has been most extensively studied in malignant melanoma. The purpose of this chapter is to discuss in depth the immunobiology and molecular aspects of lymphocyte function in general and particularly TIL function in the context of antimelanoma immunity. Emphasis is placed upon the role of these inflammatory mediators in the enhancement and impairment of progression of this often fatal human cancer. In addition, the analysis of TILs in melanoma and their direct relationship to prognosis as well as their effect on the positivity of the sentinel lymph node will be discussed. Furthermore, details of lymph node responses to metastatic melanomas and their prognostic significance will be clarified. Finally, the importance of TILs for the evaluation of therapeutic response and how TIL immunobiology could critically inform the design of novel melanoma immunotherapeutic protocols will be elucidated.

Antitumor immunity and cancer stem cells

Self-renewing cancer stem cells (CSC) capable of spawning more differentiated tumor cell progeny are required for tumorigenesis and neoplastic progression of leukemias and several solid cancers. The mechanisms by which CSC cause tumor initiation and growth are currently unknown. Recent findings that suggest a negative correlation between degrees of host immunocompetence and rates of cancer development raise the possibility that only a restricted minority of malignant cells, namely CSC, may possess the phenotypic and functional characteristics to evade host antitumor immunity. In human malignant melanoma, a highly immunogenic cancer, we recently identified malignant melanoma initiating cells (MMIC), a novel type of CSC, based on selective expression of the chemoresistance mediator ABCB5. Here we present evidence of a relative immune privilege of ABCB5(+) MMIC, suggesting refractoriness to current immunotherapeutic treatment strategies. We discuss our findings in the context of established immunomodulatory functions of physiologic stem cells and in relation to mechanisms responsible for the downregulation of immune responses against tumors. We propose that the MMIC subset might be responsible for melanoma immune evasion and that immunomodulation might represent one mechanism by which CSC advance tumorigenic growth and resistance to immunotherapy. Accordingly, the possibility of an MMIC-driven tumor escape from immune-mediated rejection has important implications for current melanoma immunotherapy.

Coexpression of major histocompatibility complex class II with chemokines and nuclear NFkappaB p50 in melanoma: a rational for their association with poor prognosis

The constitutive expression of major histocompatibility complex class II (MHC II) molecules in melanoma is highly unusual and has been associated with unfavorable clinical outcome and higher metastatic dissemination. This association remains poorly understood and therefore, in this study we looked to whether it is caused by intracellular events that promote tumor progression. We previously reported that MHC II expression in melanoma cells requires active mitogen-activated protein kinase/extracellular signal-related kinase. However, our comparative and molecular analyses of a panel of melanoma cell lines herein provide clear evidence that mitogen-activated protein kinase/extracellular signal-related kinase is not sufficient for HLA-DR expression. We found that the expression of HLA-DR in these tumors rather coincides with the expression of CXCL-1 and CXCL-8 chemokines, both known to be expressed in tumors that invade early and are related to invasive stages of melanoma. The expression of HLA-DR also nicely paralleled that of the nuclear NFkappaB p50 subunit, regulating the expression of these chemokines in melanoma and previously correlated with poor prognosis of melanoma patients, although we provide evidence that NFkappaB is not directly regulating MHC II expression level. The molecular basis for class II transactivator and HLA-DR expression in melanoma therefore remains unsolved, but our findings linking together the expression of HLA-DR, of chemokines involved in invasiveness, and of nuclear NFkappaB p50 strongly support the content that MHC II may be a marker of invasive primary melanoma, and could explain the long-standing association of MHC II expression with overall poor prognosis and unfavorable clinical outcome.

Metastatic melanoma to the palatine tonsil with a favourable prognosis

Metastasis to the oral cavity from cutaneous melanoma is rare: fewer than 30 cases of metastatic melanoma to the palatine tonsil have been reported. Tonsil metastasis is haematogenously disseminated and therefore usually has a poor prognosis. We present a case of metastatic melanoma to the palatine tonsil occurring 6(1/2) years after removal of the primary cutaneous lesion. The patient has remained disease-free for 18 months since the removal of skin and tonsil metastases. Immunohistopathologically, HLA class II and costimulatory factor B7-2 molecules were concomitantly expressed on melanoma cells: we suggest that the patient was therefore able to develop antimelanoma T-cell activation resulting in prevention of further metastasis, and thus a favourable prognosis.

Advances in specific immunotherapy of malignant melanoma

Management of malignant melanoma continues to present a challenge to dermatologists, particularly in advanced cases. In light of the steady increase in the worldwide incidence and mortality rates for melanoma, better understanding of the immune mechanisms regulating melanoma progression and interaction with the host's immune system seems eminently important. New studies on the role of immune mechanisms in the pathogenesis and clinical course of melanoma have recently been published. We review the immune mechanisms involved in tumor progression and ways in which these mechanisms may be applied toward immunotherapeutic management of malignant melanoma.

LEARNING OBJECTIVE

After the completion of this learning activity, participants should be familiar with (1) the immune mechanisms involved in host-tumor interaction and tumor rejection, (2) factors allowing the escape of melanoma cells from immune recognition, and (3) the current rationale for the different types of specific immunotherapy in melanoma. Better understanding of basic mechanisms in tumor immunology should raise awareness of future immunotherapeutic approaches in patients with melanoma, particularly in those who are at high risk of recurrence or who present with advanced disease.

Relationship between the expression of HLA-DR antigen and the effectiveness of preoperative hyperthermo-chemo-radiotherapy in oesophageal cancer

Based on the hypothesis that tumour cells expressing HLA-DR antigen would easily be damaged by the local immune response during preoperative treatments, the relationship was investigated between the expression of HLA-DR antigen in the oesophageal cancer and the effectiveness of the preoperative treatment. Immunohistochemical staining for the detection of HLA-DR antigen in cancer cells from biopsy specimens obtained before undergoing preoperative hyperthermo-chemo-radiotherapy (HCR therapy) in patients with oesophageal squamous cell carcinoma was performed, and the relationship between the expression of HLA-DR antigen and the effectiveness of HCR therapy was evaluated according to a histopathologic examination of resected specimen. A total of 35 cases were examined in which 14 showed strongly positive staining (+2), 14 weakly positive staining (+) and seven negative staining (-). No significant differences in the clinicopathologic factors between the groups were observed. In the 14 strongly positive HLA-DR antigen cases, nine were markedly effective (grade 3) (64.3%), four were moderately effective (grade 2) (28.6%) and one was slightly effective or ineffective (grade 1, 0) (7.1%). In the 14 weakly positive HLA-DR antigen cases, the markedly, moderately and slightly or ineffective cases numbered four (28.6%), eight (57.1%) and two (14.3%), respectively. On the other hand, in the seven patients showing no HLA-DR expression, the markedly, moderately and slightly effective cases numbered one (14.3%), two (28.6%) and four (57.1%), respectively. A statistical difference was observed between the cases of strongly positive and negative staining for HLA-DR antigen (p < 0.05). The expression of HLA-DR antigen in oesophageal cancer cells is thus considered to potentially be a valuable factor for predicting the effectiveness of preoperative treatment.

Comparative expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells in patients with chronic lymphocytic leukaemia (CLL)

The aim of this study was to investigate the expression of major histocompatibility complex (MHC) antigens on CD5+ and CD5- B cells of 13 patients with chronic lymphocytic leukaemia (CLL). This was carried out using a series of monoclonal antibodies (MAbs) against polymorphic and monomorphic class I and class II antigens, as well as to the transferrin receptor and assessed by flow cytometry and direct and indirect immunofluorescence. The expression of these molecules was assessed as mean fluorescent intensity (MFI). The results showed that cells from all 13 individuals expressed monomorphic class I antigens. The number of cases expressing polymorphic HLA-Bw6, -Bw4, -B7, -B27 and -A2 class I antigens on CD5- B cells was 11 (85%), 6(46%), 2(15%), 1(8%), 3 (23%), respectively, which was consistent with the expected population frequency distributions of these antigens. For each of the class I antigens on CD5+ and CD5- B cells, the ratio of the MFI was greater than 1 in 12 of 13 cases. For the transferrin receptor (CD71), this ratio was also almost always greater than 1. These results indicate that, unlike solid tumours where the loss or abnormal expression of class I and II antigens is a frequent event, the expression of class I antigens in CLL patients seems to be normal. This indicates that the loss of these antigens cannot provide the leukaemic cells with a selective advantage to escape immunological detection.

Gene therapy for melanoma in humans

As melanoma evolves, it interacts with the immune system. Based on this immunobiology, there are now a number of rationally designed attempts to develop genetically modified melanoma vaccines. This article outlines immunologic and other strategies in gene therapy for melanoma and provides an overview of current clinical trials.

Melanomas that develop within the eye inhibit lymphocyte proliferation

Experiments were performed to compare the ability of ocular and skin melanoma cells to stimulate T cells. Primary melanoma cell lines were obtained from a series of patients with either eye or skin melanoma. The ability of tumor cells to stimulate T cells in the absence of exogenous growth factors was assessed in mixed-lymphocyte tumor cell cultures in which allogeneic lymphocytes were stimulated with irradiated ocular or skin melanoma cells. Expression of HLA class I and class II on tumor cells, in the presence or absence of IFN-gamma, was determined by flow cytometry. The ability of tumor cells to inhibit T-cell proliferation was determined by adding various concentrations of irradiated tumor cells to standard mixed-lymphocyte cultures. Our results indicate that primary skin melanoma cells induce vigorous proliferation of allo-antigen-specific T cells. By contrast, ocular melanoma cells failed to induce significant T-cell proliferation. The failure of ocular melanoma cells to stimulate lymphocyte proliferation was not due to low levels of either class I or class II on tumor cells since tumor cells treated with IFN-gamma expressed high levels of class I and class II but still failed to induce lymphocyte proliferation. Ocular melanoma cells inhibited lymphocyte proliferation, as shown by experiments in which a small number of tumor cells prevented proliferation of T cells in mixed-lymphocyte cultures. Inhibition of lymphocyte proliferation required cell-to-cell contact, and supernatants from tumor cell cultures did not prevent lymphocyte proliferation. Moreover, the ability of ocular melanoma cells to inhibit T-cell proliferation was lost when tumor cells migrated from the eye and formed hepatic metastases. We conclude that there is a fundamental difference in the immunogenicity of ocular and skin melanoma cells. Ocular melanomas, but not primary skin melanomas, are poorly immunogenic tumors that inhibit T-cell proliferation. Our results imply that the immunogenicity of melanoma cells is altered when they develop within the unique ocular micro-environment.

Cytotoxic T-cell clone against rectal carcinoma induced by stimulation of a patient's peripheral blood mononuclear cells with autologous cultured tumor cells

In an effort to establish cytolytic T lymphocytes (CTLs) against colorectal carcinoma (CRC) by stimulating patients' lymphocytes with autologous tumor cells, we used peripheral blood mononuclear cells (PBMC) from a patient with minimal residual rectal carcinoma following removal of the primary lesion and involved regional lymph nodes as a source to generate CTLs in culture. A CTL line and clone were established from the patient's PBMC following stimulation of PBMC with autologous, cultured tumor cells and interleukin-2. The CTL line and the clone consisted predominantly of CD4+ lymphocytes. The CTL clone expressed two T-cell receptor variable alpha chains (V alpha11 and V alpha22) and one beta chain (Vbeta14). The cytokine secretion pattern of the CTL line was of the Th1-type. Both the CTL line and the clone lysed the autologous rectal carcinoma cells, but not the allogeneic, partially human lymphocyte antigen (HLA)-matched or nonmatched CRC cells, autologous Epstein-Barr virus-transformed B cells, K562 (natural killer target) cells or Daudi (lymphokine-activated killer target) cells. Lysis of autologous tumor cells most likely was HLA class I-restricted. Our unique success in generating CTLs against this tumor type may rest in the inclusion of a patient with minimal residual, rather than advanced, disease.

Differentiation of cultured human melanoma cells induced by the aromatic fatty acids phenylacetate and phenylbutyrate

The increasing incidence of melanoma and the poor responsiveness of disseminated disease to conventional treatments call for the development of new therapeutic approaches. Phenylacetate, a nontoxic differentiation inducer, can suppress the growth of other neuroectodermal tumors, i.e., gliomas, in laboratory models and in humans. This finding led us to explore the efficacy of phenylacetate and related aromatic fatty acids in melanoma. Phenylacetate and phenylbutyrate were found to a) induce selective cytostasis and maturation of cultured human melanoma cells, b) modulate the expression of genes implicated in tumor metastasis (type IV collagenase and tissue inhibitor of metalloproteinases-2) and immunogenicity (HLA class I); and c) enhance the efficacy of other agents of clinical interest, including retinoids, interferon-alpha, suramin, and 5-aza-2'-deoxycytidine. Reflecting on the phenotypic heterogeneity of melanoma, the degree of biologic alterations induced by phenylacetate/phenylbutyrate varied significantly among the tumor cell lines tested. Although losing invasive capacity and tumorigenicity in athymic mice, poorly differentiated cells exhibited only a marginal change in morphology, remained amelanotic, and resumed growth after treatment was discontinued. By contrast, treatment of melanoma cells that were in a more advanced stage of maturation resulted in profound alterations in cell growth, morphology, and pigmentation consistent with terminal differentiation. The in vitro antitumor activity was observed with nontoxic, pharmacologic concentrations of phenylacetate and phenylbutyrate, suggesting potential clinical use of these drugs in the treatment of melanomas.

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.

HLA-DR antigen expression in colonic adenomas and adenocarcinomas

Previous studies have shown that malignant transformation is sometimes associated with the aberrant expression of HLA class II antigens. The functional significance of such aberrant expression is not known. Since HLA-DR antigen is expressed in normal colonic mucosa, it would be interesting to see if malignant transformation could result in the aberrant suppression of this antigen. Sixteen colonic adenocarcinomas, 29 colonic adenomatous polyps and 23 samples of normal colonic mucosa, including 9 cases of colonic mucosa adjacent to carcinoma, were stained immunohistochemically for HLA-DR antigen. The intensity and distribution of the antigen staining in the cytoplasm and luminal surface of the epithelial elements were analysed semiquantitatively. The lymphoplasmacytic infiltrate in the lamina propria was also evaluated. Cytoplasmic HLA-DR antigen expression was found to be significantly diminished in moderately and poorly differentiated adenocarcinomas but not in adenomas or well-differentiated adenocarcinomas. This suggests that the change in HLA-DR expression is not intrinsic to the neoplastic process but may merely be due to the fact that malignant cells, as they become less differentiated, tend to show alterations in their antigenic phenotype.

Generation of cytotoxic T lymphocytes from peripheral blood of leukaemic patients

Peripheral blood mononuclear cells from 13 patients with acute leukaemia were used to establish long-term interleukin-2-dependent cytotoxic T lymphocytes. Cells were grown in RPMI medium containing interleukin-2 (IL-2, 100 U/ml) and 2.5% conditioned medium prepared by activating normal lymphocytes with phytohaemagglutinin. Proliferation of IL-2-dependent CD3-positive lymphocytes was seen in 1 of 2 acute lymphocytic leukaemia cases (ALL), 1 of 4 acute myelogenous leukaemia cases (AML) (M1) and 8 of 8 more differentiated AML. In 2 cases with detectable leukaemic cell markers (1 ALL and 1 AML) passageable cells were developed, that expressed normal T cell phenotypes (namely CD3, CD4 and CD8) at the expense of leukaemic cells. In 1 of 2 cases, long-term IL-2-cultured cells showed specific cytotoxic activity against autologous leukemic cells. The percentage killing against autologous and two allogeneic target cell lines at a 50/1 effector/target (E/T) ratio was 42%, 9% and 19% respectively. Similarly the cytotoxic activity of IL-2 activated from 4 different individuals against conventional tumour targets K562 and Daudi at a ratio of 50/1 was 29%-68% (median = 55%) and 34%-78% (median = 61%) respectively. It was also found that this killing potential of the activated cells was maintained for as long as culture was continued (median 23 days, range 17-75 days). The mechanism(s) of T cell proliferation at the expense of leukaemic blast cells in the case of a minority of leukaemic patients and the possible clinical therapeutic potential of these cells following in vitro IL-2 activation deserve further investigation.

Autologous melanoma vaccine induces inflammatory responses in melanoma metastases: relevance to immunologic regression and immunotherapy

Human primary malignant melanoma is often accompanied by a host response of infiltrating lymphocytes suggestive of tumor antigen-induced immunity and correlated in some tumors with prognosis. Whereas metastatic melanoma deposits typically are not inflamed and contain relatively few lymphocytes and dendritic immune cells, immunization with autologous melanoma-cell vaccine may induce a clinical inflammatory response associated with mononuclear-cell infiltration. In this study, we characterize immune responses to dermal and subcutaneous melanoma metastases in dinitrophenyl (DNP)-pre-sensitized patients immunized with DNP-conjugated melanoma cells. Patients so treated develop cutaneous delayed hypersensitivity responses to DNP-conjugated autologous mononuclear cells, and approximately one-half show clinical evidence of inflammation and regression of metastases within 2-4 months. Whereas pre-vaccination biopsies of metastatic melanoma failed to reveal significant infiltration by lymphocytes, biopsies obtained after vaccination and coincident with clinical inflammation were markedly infiltrated preponderantly by T cells with a CD8+ phenotype. Clustering of these cells about individual degenerating melanoma cells in a manner analogous to "satellitosis" was a consistent feature of this reaction. Enhanced expression of intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen (HLA)-DR by melanoma cells were invariably associated with zones of T-cell infiltration, whereas diminished or absent expression was observed in relatively unaffected regions of tumors. Numerous HLA-DR+, CD4+, CD1-, Leu-1- dendritic cells were also associated with zones of early T-cell infiltration. These data indicate that clinical inflammation and regression of metastatic melanoma induced by autologous melanoma-cell vaccine involves activated T cells with cytotoxic-suppressor phenotype and dendritic cells putatively capable of local antigen presentation. ICAM-1 upregulation on melanoma cells is a likely mediator of ligand interaction between infiltrating T cells and target cells in this model of antigen-induced host anti-tumor response. Structural alterations identified in this setting (e.g., tumor cell satellitosis) may provide additional insight into identifying features of naturally occurring host immune responses to primary cutaneous melanomas.

Prolongation of survival in metastatic melanoma after active specific immunotherapy with a new polyvalent melanoma vaccine

A new polyvalent melanoma cell vaccine (MCV) was administered to 136 stage IIIA and IV (American Joint Committee on Cancer) melanoma patients. Induction of cell-mediated and humoral immune responses to common melanoma-associated antigens present on autologous melanoma cells was observed in patients receiving the new MCV. This was accompanied by increased activation of tumor-infiltrating lymphocytes. Survival correlated significantly with delayed cutaneous hypersensitivity (p = 0.0066) and antibody responses to MCV (p = 0.0117). Of 40 patients with evaluable disease, nine (23%) had regressions (three complete). From our historical database of 126 stage IIIA and 1275 stage IV melanoma patients, there were no significant changes in the natural history of metastatic melanoma during the past 20 years. Univariate and multivariate analyses demonstrated prognostic significance for site of metastases (p = 0.0001) and immunotherapy with the new MCV (p = 0.0001). Overall our new MCV increased the median and 5-year survival of stage IIIA melanoma patients with regional soft tissue metastases twofold (p = 0.00024), and stage IV patients threefold (p = 0.0001) compared with previous immunotherapy and other treatments.

HLA-DR antigen expression in intestinal-type and diffuse-type gastric carcinoma

The expression of the HLA-DR antigen, a Class II HLA antigen, was analyzed in 41 cases of gastric carcinoma (23 intestinal-type and 18 diffuse-type according to a modified Lauren classification) using a monoclonal antibody that is reactive to this antigen in routinely formalin-fixed, paraffin-embedded tissue sections. Seventeen cases of intestinal-type gastric carcinoma and two cases of diffuse-type gastric carcinoma were positive for the HLA-DR antigen. The staining in intestinal-type carcinoma generally was stronger and more extensive than in diffuse-type carcinoma, which showed only weak and focal staining. The difference in the frequency and pattern of staining between intestinal and diffuse-type gastric carcinoma supports the concept that these are two distinct subtypes of gastric carcinoma.

Human allogeneic melanoma-reactive T-helper lymphocyte clones: functional analysis of lymphocyte-melanoma interactions

Lymphocyte clones were isolated from CD4+ peripheral-blood lymphocytes (PBL) of melanoma (Me) patient 9923 (HLA-DR7, DQw2, w6), co-cultured for 30 days with autologous accessory cells, allogeneic Me (Me 1811) (HLA-DR7, DQw1, w2), IL-1 beta (2 U/ml) and IL-2 (15 IU/ml). The 55 clones tested displayed a CD3+, CD4+, CD8-, T-cell receptor (TCR) alpha/beta+, gamma/delta- phenotype. Twenty clones were assayed for proliferation in the presence of Me 1811 and B-lymphoblastoid cell line (LCL) 1811, both expressing HLA-class-I and -II (DR7 and DQw2 shared with patient 9923), intercellular adhesion molecule-1 (ICAM-1) and lymphocyte-function-associated antigen-3 (LFA-3) molecules. Eight clones were found to be reactive to Me 1811 but not to LCL 1811. Specificity analysis of these 8 clones revealed that each of them proliferated only to Me 1811, not to other 14 Me and 12 different LCL, suggesting recognition of melanoma-associated antigen (MAA) expressed on the stimulating Me. One clone (103) was analyzed in more detail. A wider specificity analysis showed that it reacted to Me 1811 but not to 10 other Me expressing or not HLA-DR7, 5 normal melanocyte cultures (2 of them typing HLA-DR7-positive when exposed to interferon-gamma--IFN-gamma), 4 tumors other than Me and 20 different LCL. Clones did not show proliferation in the presence of autologous Me cells. Clone proliferation in response to Me 1811 was significantly inhibited by monoclonal antibodies (MAbs) directed to CD3, TCR alpha/beta, TCR beta chain V12, CD4 and HLA-DR. Moreover, following stimulation with Me 1811, clone 103 showed increased surface expression of CD25 (IL-2 receptor) and CD71 (transferrin receptor) and produced significant amounts of IL-2 and IFN-gamma. The supernatant taken from co-culture of clone 103 with Me 1811 augmented the cytotoxicity of PBL 9923 and other allogeneic PBL against K562 and Me 1811. Thus, the lymphocyte clone 103 is a CD4+ Th clone which uses its CD3/TCR alpha/beta complex to recognize an MAA in conjunction with HLA-DR7. Availability of this type of reagent may prove useful to identify and characterize MAA recognized by T lymphocytes.

Effects of interferon-gamma and tumour necrosis factor-alpha on the development of cytotoxic T lymphocytes in autologous mixed lymphocyte tumour cultures with human melanoma

We have studied the influence of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) on the development of cytotoxic T lymphocytes (CTL) against melanoma in mixed lymphocyte tumour cultures (MLTC). In these MLTC, TNF-alpha at 10(4) U/ml increased the expansion of the CTL up to 10(4)-fold over recombinant IL-2 (rIL-2) alone. IFN-gamma at 10(4) U/ml and combinations of TNF-alpha plus IFN-gamma at 10(2)-10(3) U/ml promoted the proliferation more variably. MLTC generated with rIL-2 showed a predominance of CD8+ cells, while 2 weeks of culture in the presence of IFN-gamma at 10(4) U/ml, or with IFN-gamma and TNF alpha at 1 x 10(2)-10(3) U/ml, favoured the emergence of CD4+ cell populations. The cytotoxic activity of the lymphocytes generated in these MLTC showed a consistent decline of K562 cytotoxic activity following exposure to the combination of IFN-gamma and TNF-alpha. Despite the altered T cell subset distribution with different combinations of cytokines, no consistent alteration in the specific anti-tumour cytotoxicity against melanoma was detected. These results suggest that TNF-alpha and IFN-gamma influence the activation, phenotypic, and functional outcome of MLTC-generated CTL, and may account for the phenotypic variations observed in T cell populations generated in vitro.

Cell adhesion molecules of the immunoglobulin supergene family and their role in malignant transformation and progression to metastatic disease

Cell adhesion molecules (CAMs) of the immunoglobulin supergene family may play important roles in tumorigenesis and the development of metastatic disease. In a variety of human malignancies, tumor progression has been observed to be associated with changes in CAM expression. An early event in colorectal tumorigenesis appears to be the down regulation of a normally expressed CAM, DCC. Over-expression of a second CAM, carcinoembryonic antigen, is associated with colorectal tumors which have a high risk for metastasis development. Several tumors, including Wilms tumors and neuroblastoma, have been found to express a developmentally regulated form of NCAM which inhibits a variety of cell-cell interactions. Malignant cells not only show aberrations in the expression of their CAMS and thus their normal cell-cell interactions, but establish new adhesive interactions. The development of metastatic potential in cutaneous melanoma is associated with the de novo expression of two CAMs, one of which is ICAM-1, a molecule mediating adhesion between the tumor cells and leukocytes.

Lacking prognostic significance of beta 2-microglobulin, MHC class I and class II antigen expression in breast carcinomas

To evaluate the impact of MHC antigen expression on the survival of patients with cancer, 77 human breast carcinomas were investigated for the expression of beta 2-microglobulin (beta 2m), HLA-A,B,C and HLA-DR. Thirty-one benign breast tumours were stained for comparison. The results for the carcinomas were related to the survival data of the cancer patients. The expression of beta 2m, HLA-A,B,C and HLA-DR was significantly lower in malignant tumours compared to the benign lesions. Whereas all benign tumours were positive for beta 2m and HLA-A,B,C and 28/31 positive for HLA-DR the following positivity rates were found in carcinomas: 74/77 for beta 2m, 57/77 for HLA-A,B,C and 10/77 for HLA-DR. The follow-up (median 45 months) of 66 cancer patients for overall survival and of 65 patients for disease-free survival revealed no influence of beta 2m, HLA-A,B,C or HLA-DR expression on the prognosis of this cancer. In conclusion, experimental data indicating the importance of MHC antigens in anti-tumour responses are not confirmed by the analysis of cancer patient survival data.

Immunohistological relation between DR antigen expression on melanoma cells and infiltration by CD8+ T cells

Previous studies have suggested that class II major histocompatibility (MHC) antigen expression on melanoma cells may influence immune responses against melanoma and the nature of lymphocytic infiltrates against the tumor. This question was examined further by immunoperoxidase studies on sections from 29 primary and 30 metastatic melanoma with monoclonal antibodies (MAbs) against different lymphocyte subsets. The results indicated that expression of MHC class II DR* antigens on melanoma cells was associated with increased overall lymphocytic infiltration and that this applied particularly to the CD8+ subset of T cells. The CR3 receptor (CD 11b) was expressed predominantly on T cells and not macrophages but infiltration by CD11b+ cells did not correlate strongly with DR expression on melanoma cells. Dual staining with MAbs to CD8 and CD11b revealed that, whereas most of the CD8+ cells in DR- primary melanoma and DR+ metastatic melanoma were CD11b+, only approximately 50% of the CD8+ cells in DR+ primary melanoma were also CD11b+. Expression of CD11b on T cells was reported to define a suppressor subset of T cells. If the latter is correct the present results suggest that DR expression on primary melanoma is associated with infiltration by the cytotoxic T cell subset, whereas in the absence of DR antigens and in metastases this subset is absent and the predominant subset appears to be CD8+ CD11b+ T cells with suppressor activity. The biologic and prognostic significance of these findings remains to be determined.

Human IgG and IgM monoclonal antibodies against autologous melanoma produced by Epstein-Barr-virus-transformed B lymphocytes

The serum antibody response to human melanoma has prognostic and potential physiological consequences. The specificity of the host B cell antibody response may be an important determinant of disease outcome. We have utilized Epstein-Barr virus (EBV) transformation to analyze the repertory of the host B cell response to melanoma. Production of antibody that binds selectively to autologous (eight cases) or allogeneic (four cases) short-term-cultured melanoma cells was assessed from EBV-transformed B lymphoblastoid cells. Forty-two cultures of EBV-transformed B cells that secreted IgM and 23 that secreted IgG antibodies gave patterns of differential reactivity with autologous or allogeneic melanoma. Antibody-forming B cells persisted in producing melanoma-reactive IgG and IgM for 8-21 weeks. Preselection of B cells by adsorption to tumor cell antigens before transformation enhanced the frequency of antibody secretion. The specificity of the antibody produced by the longest-producing culture appears to be restricted to a subset of melanomas. The patient from whom this tumor-restricted IgG-producing B cell was retrieved was unusual, having had a transient serum IgG of similar specificity, and having manifest a syndrome of vitiligo at the time of her development of serum antimelanoma antibody, followed by disease-free survival of resected recurrent metastatic melanoma to the present (more than 6 years). This study has given support to findings of conventional serology, revealing the production of melanoma-reactive antibody from B cells of patients who have demonstrable serological response to tumor.

Immunobiology of brain tumors

In summary, many actual interactions between tumors in the CNS and the immune system have been demonstrated. The normal brain does not possess a lymphatic system and is partially hidden from the systemic immune system by the BBB, furthermore brain cells do not express MHC antigens which are necessary for the initiation of an immune response. In pathological conditions however, immunocompetent cells may find their way through transformed endothelial cells. Microglia and astrocytes may function as antigen presenting cells. Glioma cells when stimulated by cytokines such as IFN gamma can be induced to express MHC class I and class II antigens, thus making them more susceptible to an immune attack. In addition glioma cells are capable of secreting several cytokines including IL 1, IL 3 and IL 6 also involved in the generation of an immune response. Indeed, a functional analysis of lymphocytes infiltrating gliomas has revealed the accumulation at the tumor site of cytotoxic T lymphocytes as well as NK cells. However host-immune responses against gliomas seem to be weak in comparison to other cancers. Glioma cells are known to secrete TGF beta 2 and PGE 2 which may in part be responsible for this lack of immune response, thus shielding themselves from immune attack. In order to be recognized by the immune system the tumor cells must express TAA in addition to MHC antigens, and such TAA have been identified by MAbs. These MAbs can be used for "targeted" therapy when coupled to toxic agents or radionuclides. Preclinical studies have shown that, after intravenous or intracarotid injection, there is specific accumulation of the MAb in the tumor but in insufficient amounts for therapeutic use. The relatively small amount of MAb binding to the tumor in vivo can be due to several factors: not all the cells in a single tumor express a given tumor-associated antigens, the MAb may have a low affinity for the antigen, the BBB may hinder the passage of the MAb. Attempts have been made to overcome these drawbacks by opening the BBB for example. In addition MAbs can readily be used for the treatment of carcinomatous meningitis. There has been little success in the development of immunotherapy with IFN beta 1 and even less with adoptive immunotherapy using LAK cells plus IL 2. TIL as well as LAK cells can be expanded in vitro with IL2 and it is feasible to reinject these cells into the tumor site.(ABSTRACT TRUNCATED AT 400 WORDS)

Infection of bovine T cell clones with genotypically distinct Theileria parva parasites and analysis of their cell surface phenotype

Different stocks and stabilates within a stock of Theileria parva were analysed for genotypic differences and for their effect on the expression of host cell surface antigens following infection of BoT8+ T lymphocyte clones. The parasites were characterized in vitro by hybridization of T. parva-specific DNA probes to Southern blots of endonuclease-digested DNA from the infected T cell clones. Phenotypic changes in the host lymphoblastoid cells before and after infection were examined using lineage-specific monoclonal antibodies which reacted with the differentiation antigens BoT2, BoT4, Bo6, BoT8 and a null cell marker on bovine T cells. Expression of Class I and Class II major histocompatibility complex (MHC) antigens on the cell populations was also assessed. Results of this study indicate that genotypically different parasites exist among and within T. parva stabilates and that the expression of Bo6, BoT8 and the null cell marker was differentially altered by infection with parasites from different stocks or from different stabilates of the same stock. Expression of Class II antigens was significantly increased after infection. Moreover, clones that were derived from the same cell line but had genotypically distinct T. parva parasites, also showed differences in expression of Bo6 and BoT8 and the null cell marker.

Clonal analysis of cytotoxic and regulatory T cell responses against human melanoma

T cell-mediated immune response against autologous melanoma cells was analyzed, at population and clonal levels, in 31 patients with recurrent and/or metastatic disease. Fresh PBL and lymph node lymphocytes (LNL) from melanoma-involved nodes were not cytotoxic against the respective melanoma cells. When activated in in vitro coculture (IVC) against the autologous melanoma cells in the presence of IL-2, a majority of the activated PBL and LNL became cytotoxic against the autologous targets. The activated effector cells were cloned in limiting dilution microcultures, and growing clones were phenotypically defined and were functionally characterized for cytotoxicity and for potential regulatory function. Functional T cell clones were obtained from 15 of 31 cases. Of these, CTL responses exhibiting cytotoxicity restricted against the autologous melanoma were seen in four cases. All four CTL clones were CD3+, CD8+, and CD4-. Three of these four CTL clones were studied extensively. All three of these CTL clones expressed MHC class I-restricted cytotoxicity. mAb anti-CD3 blocked cytotoxicity in two and enhanced cytotoxicity in the other. Neither autologous sera nor autologous nonactivated fresh PBL modulated the cytotoxic functions of the CTL clones at the effector phase. T cell lines exhibiting regulatory function were obtained in 11 cases. The regulatory T cell lines were CD3+, CD4+, and CD8-. In three cases CD4+ clones amplified the cytotoxic response in the PBL in coculture, while in eight other cases the T cell lines downregulated the cytotoxic responses. Such T cell-mediated down-regulations were either restricted to the autologous system, induced by D/DR antigens expressed by the autologous or allogeneic melanoma cells, or induced by stimulus other than D/DR antigens. Taken together, these findings clearly demonstrate the existence of T cell-mediated cytotoxic and regulatory responses against human melanoma.

HLA-DR expression by high grade superficial bladder cancer treated with BCG

The local immune response to intravesical BCG therapy for widespread carcinoma in situ and superficial bladder tumour was assessed using immunohistochemical methods on serial biopsies obtained during treatment. The main findings were the induction of a strong level of HLA-DR expression by urothelial cells which persisted for several months after completion of therapy. This coincided with a mononuclear cell infiltrate in the bladder wall consisting predominantly of activated helper T lymphocytes. Smaller numbers of macrophages, suppressor cytotoxic T lymphocytes and B lymphocytes were also found. These new findings confirm that the inflammatory response to BCG involves the urothelium in an immunological reaction and suggest that the success of immunotherapy with intravesical BCG may be due to enhanced tumour antigen recognition.

Characterization of activated lymphocytes in colon cancer

The percentages of activated lymphocytes in colon cancers were compared to clinical features of the tumors and to functional characteristics of the tumor-infiltrating lymphocytes (TIL) in order to evaluate the role of activated TIL in controlling tumor growth. The TIL isolated from colon cancers contained 80 +/- 6% T cells [cluster designation (CD) 2+], 42 +/- 9% CD4+ cells, 27 +/- 9% CD8+ cells, 17 +/- 5% cells (surface immunoglobulin or SIg+), 6 +/- 2% null cells (CD2-, SIg-), 6 +/- 4% Leu 7+ cells, 1 +/- 0% macrophages (CDw 14+), and no plasma cells (PCA+). The lamina propria lymphocytes (LPL) isolated from adjacent colonic mucosa contained a similar distribution but with fewer CD8+ (10 +/- 5%) and Leu 7+ (0.6 +/- 0.3%) lymphocytes (P less than 0.05). More TIL than LPL expressed the interleukin-2 (IL-2) receptor (9 +/- 8% vs 1 +/- 0.8% CD25+ cells; P less than 0.05) and the transferrin receptor (4 +/- 5% vs 0.3 +/- 0.6% T9+ cells; P less than 0.05). Those TIL expressing activation antigens were CD2+, SIg-. The percentage of TIL that were CD25+ did not correlate with the extent of tumor spread, with the degree of tumor differentiation, nor with the percentage of HLA-DR+ tumor cells. However, there were significantly more CD25+ TIL from tumors located in the left colon, particularly small lesions, than from tumors located in the right colon (P less than 0.05). The proliferation of TIL preparations cultured with medium alone, with mitogens, or with IL-2 did not vary according to the percentage of CD25+ lymphocytes in the TIL. T cells may be activated by foreign surface determinants on tumor cells, particularly in small, left-sided lesions.

Accessory cell function of human melanoma cells in mitogen-induced T cell proliferation

Six out of eight human melanoma cell lines were found to be able to function as accessory cells in PHA-induced proliferation of autologous and allogeneic T cells. The accessory cell function of the melanoma cell lines appears to be similar to that of monocytes, requires the presence of viable cells, and does not correlate with the cell surface binding sites for PHA and with the level of expression of HMW-MAA and of HLA Class I antigens. HLA Class II antigens do not appear to play a major role in these phenomena, since there is no relationship between level of expression of HLA Class II antigens and accessory cell function of melanoma cells. Furthermore, addition of anti-HLA Class II monoclonal antibodies does not affect proliferation of T cells stimulated with PHA in the presence of melanoma cells with accessory cell function. Although melanoma cells exert accessory cell function, functional and immunological assays did not detect IL-1 in the spent medium of the melanoma cell lines. Furthermore, Northern blotting analysis with IL-1 alpha and IL-1 beta probes did not detect IL-1-specific mRNA in melanoma cell lines. These results suggest that PHA-induced proliferation of T cells in the presence of melanoma cells can bypass the requirement for IL-1 or utilizes factors other than IL-1.

IFN-treatment of B16-F1 versus B16-F10: relative impact on non-adaptive and T-cell-mediated immune defense in metastatic spread

Treatment of tumor cells with interferon-gamma (IFN) frequently reduces their susceptibility towards NK cells and results in augmented expression of MHC antigens, which may increase immunogenicity of tumor cells. Depending on the relative strength of these opposing effects, i.e. escape from non-adaptive immune defense versus facilitated activation of T-cell-mediated defense, IFN-treatment may be beneficial or disadvantageous for the tumor-bearing host. This is demonstrated for the variants F1 and F10 of the B16 melanoma, which differ in metastasizing capacity. IFN-treatment of B16-F1 melanoma cells significantly reduced susceptibility towards non-adaptive immune defense, and increased metastasizing potential. On the other hand, H2K antigen expression was augmented by a factor of 50; concomitantly, lysability by CTL was increased, together with the number and expansion rate of cytotoxic T-cell precursors (CTLp) recruited after immunization with IFN-treated B16-F1. The benefit of increased antigenicity and immunogenicity outweighed the disadvantage or reduced susceptibility towards non-adaptive immune defense. B16-F10 cells were less susceptible to NK cells, expression of MHC antigens was found to be stronger and they were more immunogenic than B16-F1 cells. After IFN-treatment, susceptibility to non-adaptive immune defense was further reduced. Expression of MHC antigens as well as antigenicity and immunogenicity were only moderately augmented. As a consequence, the decreased susceptibility to non-adaptive immune defense was dominating in the tumor bearing host and could not be counterbalanced by immunization with IFN-treated B16-F10 cells. We interpret these data to show that a precise knowledge of the relative decrease in susceptibility to non-adaptive immune defense, the relative increase in MHC antigen expression, antigenicity and immunogenicity may allow a more precise prognosis of the influence of IFN on metastatic capacity in the B16 system, and eventually also in a clinical therapeutic regimen.

Proliferative and/or cytotoxic activity of lymphocyte clones to autologous human melanoma

Peripheral blood lymphocytes (PBL) of a patient with metastatic melanoma were cultured with autologous melanoma cells (Auto-Me) and recombinant interleukin 2 (IL-2) (MLTC-PBL). Thirty-five days later, when no cytotoxicity against Auto-Me or K562 was detectable, MLTC-PBL were cloned in the presence of Auto-Me, IL-2 (25 U/ml) and Daudi cells as feeder. Eighty-one growing clones were simultaneously screened for proliferative and cytotoxic activity to Auto-Me. Twenty-two clones proliferated in the presence of Auto-Me only, 29 in the presence of IL-2 only and 41 in the presence of Auto-Me plus IL-2; 12 clones showed cytotoxic activity against Auto-Me. Six clones expressed both cytotoxic and proliferative activity to Auto-Me. The phenotype of 6 proliferative clones tested was CD3+, CD4+, WT31+, CD8-, CD16-, Leu19-, whereas that of 2 cytotoxic-proliferative clones tested was CD3+, CD8+, Leu19+, WT31+, CD4-, CD16-. Specificity analysis of proliferative response of 6 clones and of cytotoxicity of 7 clones, tested on a panel of 14 different target cells, revealed a complex pattern of reactivity, each clone expressing a peculiar specificity. Our results suggest the possibility of isolating, from melanoma patients' PBL, T-cell clones with proliferative activity to Auto-Me and Auto-Me plus IL-2, and T-cell clones which apparently express both proliferative and cytotoxic activity to Auto-Me.

Differential expression of HLA-DR, DQ, and DP antigens in primary and metastatic melanoma

Fifty-five primary and 33 metastatic surgically removed melanoma lesions were stained in indirect immunoperoxidase with anti HLA-DR, DQ, and DP monoclonal antibodies and with the monoclonal antibody CL203.4 to a 96-K melanoma associated antigen (MAA). The latter antigen may represent a marker to monitor susceptibility of melanoma cells to modulation by IFN-gamma, because it is highly susceptible to induction by IFN-gamma. In primary melanomas 44%, 29%, 10%, and 55% of the lesions tested were evidently stained by anti HLA-DR, DQ, DP, and 96-K MAA monoclonal antibodies, respectively. A statistically significant association (P less than 0.01) was demonstrated between the degree of intratumoral lymphocytic infiltrate and the expression of HLA-DR and HLA-DQ antigens. In addition, a high degree of concordance in the reactivity pattern of individual lesions stained for HLA-DR antigens and for the 96-K MAA was found. In metastases 64%, 33%, 47%, and 100% of the lesions tested were evidently stained by anti HLA-DR, DQ, DP, and 96-K MAA monoclonal antibodies, respectively. This study indicates that HLA-DR and HLA-DP antigens are expressed in a higher percentage of metastatic than of primary melanomas and that there is no marked difference in the expression of HLA-DQ antigens between primary and metastatic melanomas. The data suggest that the regulatory mechanisms which control the expression of HLA-DR and DP antigens in primary and metastatic melanoma lesions are different. Locally produced IFN-gamma may play a role in the regulation of HLA Class II antigens in primary melanomas.

Inflammatory cell infiltrates in human melanoma at different stages of tumor progression

Progression of human melanoma is associated with changes in antigenic phenotypes of tumor cells. To establish whether inflammatory infiltrates in progressing melanoma also change, we studied 146 cutaneous melanomas at different stages of progression. Monoclonal antibodies (MAbs) against lymphocyte and macrophage subpopulations, interleukin-2 receptor (IL-2 R), immune interferon (IFN-gamma), and the IFN-gamma-inducible, progression-associated melanoma antigens HLA-DR and gp89 were applied in situ. During the course of melanoma progression, decreased amounts of peritumoral T cells, IL-2 R-expressing lymphocytes and dermal T6+ dendritic cells were found, while increased numbers of intratumoral T cells, inflammatory (27E10+) and mature (25F9+) macrophages were associated with local progression of primary melanomas. In metastases, most infiltrate components except 25F9+ macrophages were rare. Positive correlations were observed between: (1) dermal T6+ cells and IL-2 R+ lymphocytes, and (2) presence of IFN-gamma in the infiltrate and HLA-DR and gp89 antigens on tumor cells. In all stages, HLA-DR expression on tumor cells was correlated with: (1) a shift towards T8+ lymphocytes in the infiltrates and (2) a loss of IL-2 R expression. Our data suggest mutual influences between melanoma cells and mononuclear cell infiltrates in situ.

Interferon-gamma treatment of B16 melanoma cells: opposing effects for non-adaptive and adaptive immune defense and its reflection by metastatic spread

The impact of interferon-gamma (IFN) treatment of tumor cells on non-adaptive and adaptive immune defense and its reflection by metastatic spread were evaluated using a weakly metastasizing variant of B16 melanoma (B16-FI). Treatment of B16-FI with IFN resulted in a decrease in binding structures for NK cells and concomitantly in augmented metastasizing capacity. In line with this, activation of NK cells and Mo, which led to reduction of metastatic nodes, was less efficient with IFN-treated B16-FI, while after elimination of non-adaptive immune defense, the number of metastases increased significantly, but irrespective of IFN treatment. On the other hand, IFN-treated B16-FI cells become more prone to killing by cytotoxic T-cells (CTL). This was due to increased lysability by CTL and to increased immunogenicity; i.e., a higher frequency of B16-specific CTL was observed after immunization with IFN-treated than with untreated B16-FI. The reverse phenomenon was observed with anomalous and/or lymphokine-activated killer cells (AK/LAK). The common cause of increased antigenicity and immunogenicity may reside in increased expression of class-I and de novo expression of class-II MHC antigens after IFN treatment. Increased antigenicity and immunogenicity of IFN-treated B16-FI was reflected by significant reduction of metastatic nodes, prolonged survival and increased TD100 in animals immunized with IFN-treated vs. untreated melanoma cells. Comparison of the divergent effects of IFN treatment on B16-FI melanoma cells showed that the benefit of increased antigenicity/immunogenicity clearly outweighed the disadvantage of reduced susceptibility to non-adaptive immune defense.

Characteristics of cultured human melanocytes from different stages of tumor progression

Based on the clinicopathological delineation of distinct steps of tumor progression in the melanocytic system, the in vitro behavior of melanocytes with increasing malignant potential has been investigated. Tumor progression in melanocytes is characterized by an increasing growth autonomy and decreased requirement but enhanced utilization of exogenously provided polypetide growth factors (EGF, IGF-I). The endogenous production of growth factors such as alpha-TGF, PDGF, and bFGF by metastatic melanoma cells might contribute to their independence from exogenously provided factors. Although expression of some melanoma-associated antigens in vivo is detectable only on malignant cells, propagation of normal melanocytes in tissue culture leads to expression of the majority of these antigens. Many of these antigens can be grouped into functionally defined categories, including growth factor receptors, extracellular matrix proteins, and cell-substrate interacting antigens. One cell-substrate interacting antigen, the GD2/GD3 ganglioside, appears to play a critical role in the metastatic process of melanoma cells. The successful propagation and characterization of melanocytic cells of all stages of tumor progression in tissue culture provide a unique human experimental model for the study of mechanisms of malignant transformation.