MHC-restricted responses of CD8+ and CD4+ T-cell clones from regional lymph nodes of melanoma patients

Proteomic Implications of Tumoral Infiltrating Lymphocytes in Melanoma: PD-L1, CD4 and CD8 - Short Review

Melanoma is a tumor developed by malignancy of melanocytes, being one of the most lethal cancers. Usually, it is associated with exposure to ultraviolet radiations, being most common in the skin, but can also be located extracutaneously as in the digestive tract, leptomeninges or uvea. Histopathologically it presents a phase of radial growth and a vertical one, often accompanied by an intra and peritumoral inflammatory infiltrate. Immunohistochemically, the confirmation of the diagnosis of melanoma should be accompanied by the assessment of proteomic markers of lymphocytic infiltrate such as PD-L1, CD4 and CD8. Those have a role in evaluating the prognosis and a possible prediction of the immunotherapeutic response.

Peripheral Blood CD4+ T-Cell Response Before Postoperative Active Immunotherapy Correlates with Clinical Outcome in Metastatic Melanoma

BACKGROUND

Canvaxin polyvalent specific active immunotherapeutic (CancerVax Corp., Carlsbad, CA) is a minimally toxic adjuvant after resection of regional metastatic melanoma. Because Canvaxin immunotherapeutic requires induction of an immune response, we hypothesized that survival would be directly correlated with cellular immune responses to Canvaxin cells prior to immunization.

METHODS

We randomly selected 54 patients from a study of Canvaxin therapy after complete resection of American Joint Committee on Cancer (AJCC) stage III melanoma. Peripheral blood lymphocytes (PBLs) collected before immunotherapy were co-cultured with Canvaxin cells; cellular response was determined by flow cytometric measurement of the production of intracellular interleukin 4 (IL4) or interferon gamma (IFNgamma) by CD4(+) T-cells. Results were calculated as percent positive for double staining of CD4(+) plus IL4(+) or CD4(+) plus IFNgamma(+).

RESULTS

The mean (+/- SD) increase in cytokine-producing CD4(+) T-cells after Canvaxin stimulation was 4.8 +/- 2.3% for an IFN response and 5.1 +/- 2.0% for an IL4 response. Both increases were significantly correlated with overall survival by univariate analysis (P = .0471 for IFNgamma and 0.002 for IL4). There was no significant correlation between unstimulated IFNgamma/IL4 responses and overall survival. Multivariate analysis showed that a CD4(+) T-cell IL4 response before Canvaxin therapy was a significant independent prognostic variable.

CONCLUSIONS

In vitro cellular immune response to Canvaxin cells directly correlates with survival after subsequent initiation of immunotherapy for AJCC stage III melanoma. This finding will be evaluated in a multicenter phase III trial of Canvaxin plus bacille Calmette-Guerin (BCG) versus placebo plus BCG after resection of stage III melanoma.

Modulation of tumor growth by crossreacting isoantibodies

Tumor cells transfected with strong antigenic epitopes were able to stimulate humoral response against relevant wild-type tumors. Crossreacting immune sera have been obtained by immunizing C57BL/6 mice with OVA-transfected leukemia EL-4 (subclone E.G7) and OVA-transfected melanoma B16 (subclone MO.5) stimulated with interferon-gamma. Tumors were significantly inhibited when antisera were injected subcutaneously close to the site of solid wild-type tumors EL-4 and B16 grafted onto C57BL/6 mice.

Tumour cell-based vaccines for the treatment of melanoma

Melanoma is generally resistant to chemotherapy and radiation therapy. Its unique immunological properties lend support to developing innovative new therapies via manipulation of the patient's own immune system. The use of whole-cell-based tumour vaccines, including autologous, whole-cell allogeneic and cytokine gene-modified vaccines, as well as tumour lysate vaccines, for active specific immunotherapy of melanoma, is discussed in detail with regard to rationale and available clinical data. Although phase II data on the use of melanoma vaccine in the adjuvant setting show promise, there is no randomised phase III trial demonstrating the efficacy of active specific immunotherapy for melanoma. The coming years will bring the results of several pivotal multicentre phase III trials testing the clinical utility of active specific immunotherapy in the management of melanoma.

Immunohistologic responses within dermal metastatic melanoma lesions of patients treated with a synthetic peptide vaccine

Three patients with dermal metastatic melanoma lesions responding to a synthetic peptide vaccine (g209-2M) derived from the sequence of gp100 melanoma-associated antigen, along with either IL-2 or granulocyte-monocyte colony-stimulating factor were studied to characterize the immunologic response occurring within and around the lesions during therapy. Standard immunocytochemical techniques were used to study the T-cell response (CD3, CD4, and CD8), the B-cell response (CD20), and the expression of class II major histocompatibility complex (HLA-DR) antigens. Between 40 and 65 days after the initiation of vaccine therapy (more than 3 weeks after the second dose of vaccine), the gross tumor size decreased and the tumors from all three patients showed substantial histologic regression associated with increased numbers of tumor-infiltrating lymphocytes and melanophages. The increased lesional tumor-infiltrating lymphocytes consisted of CD3+ T cells and very few CD20+ B cells. In two of the three patients, the T-cell infiltrate occurring during the initial tumor regression consisted predominantly of CD8+ cells. The number of perivascular T cells surrounding small vessels adjacent to melanoma lesions also increased during the time of peak histologic tumor regression. Also during the course of vaccine therapy, the expression of HLA-DR by vascular endothelial cells of the small vessels adjacent to lesions increased in all three patients, and elevated endothelial expression of HLA-DR was maintained in two of the three patients. These results show that patients with metastatic melanoma, who responded to melanoma vaccine therapy, had a predominantly CD8+ T-cell infiltrate associated with a loss of tumor cells. As the tumor cells diminished, they were replaced by heavily pigmented melanophages.

Recognition of breast cancer-associated peptides by tumor-reactive, HLA-class I restricted allogeneic cytotoxic T lymphocytes

Strategies to identify tumor-associated antigens rely on the paradigm that tumor-associated peptides presented in the context of HLA-class I are recognized by the cellular immune system. Approaches to isolate tumor-specific cytotoxic T lymphocytes (CTL) from tumor-infiltrating lymphocytes are difficult because long-term growth of the CTL requires autologous tumor cells and lymphocytes (PBL) as feeder cells. In this study, a CTL line (BL.HBL-100 CTL) was generated from PBL from a normal healthy donor by stimulating with irradiated, HLA-class I partially matched breast cancer cell line HBL-100. Activated T lymphocytes generated expressed TCR alpha/beta+ with a predominant CD8+ population after 12 stimulations (98.54% CD8+ vs. 0.18% CD4+). These CTL lysed HLA-A1+, but not HLA-A1-, breast cancer cell lines. Moreover, HLA-A1+, non breast cancer cell lines were not recognized. The lytic activity of BL.HBL-100 CTL against HLA-A1+ breast cancer cell lines was blocked by monoclonal antibodies (MAbs) to HLA-class I and CD8, but not by anti-HLA-class II and CD4. Recognition of HLA-A1+ breast cancer cells by the CTL was dependent on peptides associated with HLA-class I since the lysis was inhibited by acid elution of HLA bound peptides. HBL-100 tumors were grown in severe combined immunodeficient (SCID) mice. Immunohistochemical staining of the HBL-100 tissue harvested from SCID mice demonstrated human breast cancer cells. HLA-class I molecules were affinity purified from the HBL-100 harvested from the SCID mice; class I bound peptides were eluted and separated by RP-HPLC. Pooled HPLC peptide fractions were tested for reconstituting antigenic epitopes recognized by the BL.HBL-100 CTL and found to reside within fraction 40. Our results show that a tumor reactive, HLA-class I restricted CTL was produced by stimulating normal PBL against an HLA-class I matched breast cancer cell line. We also provide evidence for a breast cancer-associated, HLA-class I bound peptide antigen(s) that reconstitutes the antigenic epitope(s) recognized by these CTL.

Control of Syngeneic Tumor Growth by Activation of CD8+ T Cells: Efficacy Is Limited by Migration Away from the Site and Induction of Nonresponsiveness

Activation of Ag-specific CD8+ T cells in response to syngeneic tumor has been visualized by adoptive transfer of CD8+ T cells from OT-I mice, with a transgenic TCR specific for H-2Kb and an OVA peptide, into Thy-1 congenic recipients. Intraperitoneal challenge with E.G7, the EL-4 thymoma transfected with OVA, results in activation and clonal expansion of the OT-I cells in the peritoneal cavity and transient control of tumor growth. However, within 2 days after becoming activated, the OT-I cells migrate out of the peritoneal cavity into the spleen and lymph nodes, and tumor growth resumes in the peritoneal cavity. The OT-I cells in lymph nodes and spleen have lytic effector activity, but exhibit split anergy in that they cannot proliferate in response to Ag unless exogenous IL-2 is provided. The failure to remain at the tumor site and continue to control tumor growth is not due to selection of Ag loss variants or development of suppression. These results suggest that effective CD8-targeted immunotherapy may depend less on enhancing the initial activation and more on sustaining the response at the appropriate location and/or reactivating cells that have left the site of tumor growth and become nonresponsive.

CD4 T cells kill melanoma cells by mechanisms that are independent of Fas (CD95)

Previous studies have shown that CD4 T cells are associated with regression in primary melanoma and rejection of tumors in adoptive transfer models. The mechanism by which they mediate their anti-tumor effects remains unclear, and some studies have suggested that Fas ligand (FasL)/Fas interactions were involved. In the present study, we have examined the cytotoxic mechanism involved in CD4 T-cell killing of melanoma cells and, in particular, the role of FasL/Fas interactions in this killing. We show that the CD4 T cells in 4 clones of T cells induced apoptosis in autologous melanoma cells by MHC-restricted mechanisms but lysed an allogeneic melanoma cell by a non-apoptotic mechanism. Melanoma cells expressed both Fas and FasL, but killing of melanoma cells did not involve Fas/FasL interactions. This was shown by a lack of correlation between Fas expression and susceptibility to lysis and by failure of a monoclonal antibody to Fas to block killing by the CD4 T cells, though the latter expressed FasL. Recombinant FasL did not induce killing of melanoma cells.

Distinct intracellular compartments involved in invariant chain degradation and antigenic peptide loading of major histocompatibility complex (MHC) class II molecules

Major histocompatibility complex (MHC) class II molecules are transported to intracellular MHC class II compartments via a transient association with the invariant chain (Ii). After removal of the invariant chain, peptides can be loaded onto class II molecules, a process catalyzed by human leukocyte antigen-DM (HLA-DM) molecules. Here we show that MHC class II compartments consist of two physically and functionally distinct organelles. Newly synthesized MHC class II/Ii complexes were targeted to endocytic organelles lacking HLA-DM molecules, where Ii degradation occurred. From these organelles, class II molecules were transported to a distinct organelle containing HLA-DM, in which peptides were loaded onto class II molecules. This latter organelle was not directly accessible via fluid phase endocytosis, suggesting that it is not part of the endosomal pathway. Uptake via antigen-specific membrane immunoglobulin resulted however in small amounts of antigen in the HLA-DM positive organelles. From this peptide-loading compartment, class II-peptide complexes were transported to the plasma membrane, in part after transit through endocytic organelles. The existence of two separate compartments, one involved in Ii removal and the other functioning in HLA-DM-dependent peptide loading of class II molecules, may contribute to the efficiency of antigen presentation by the selective recruitment of peptide-receptive MHC class II molecules and HLA-DM to the same subcellular location.

Interactions between autologous CD4+ and CD8+ T lymphocytes and human squamous cell carcinoma of the head and neck

The autotumor (AuTu)-specific cytolytic T lymphocyte (CTL) line established from the peripheral blood of a patient with oral squamous cell carcinoma (Cancer Res. 53, 1461, 1993) contained >95% of CD8+ and <5% of CD4+ T cells. This CTL line was infected with Herpesvirus saimiri to increase its life span in culture. Two transformed T cell sublines were obtained: the monoclonal CD4+ line (TCR Vbeta2+ V alpha15+) and the oligoclonal CD8+ line (TCR Vbeta6+, Vbeta7+ and Vbeta9+) both of which were maintained in culture for >6 months without AuTu restimulation and which did not produce any virus. The virus-transformed and untransformed T cell lines were compared for phenotypic and functional characteristics, including the ability to kill AuTu, induce expression of the major histocompatibility complex (MHC) antigens on AuTu, and respond to AuTu by cytokine production and/or proliferation. The H. saimiri-transformed CD4+ T cells expressed higher levels of surface adhesion molecules and CD45RO than untransformed cells and lysed AuTu by inducing DNA fragmentation as well as necrosis. This lysis was inhibited by antibodies to CD4 but not to class I or II MHC molecules. The CD4+ T cells produced IL2, TNF-alpha, and GM-CSF and proliferated in response to AuTu. They induced and sustained proliferation of CD8+ T cells in cocultures with AuTu. Supernatants obtained from cocultures of the CD4+ T cells with AuTu also induced proliferation of the CD8+ T cell line. In contrast, the H. saimiri-transformed CD8+ T cells did not kill AuTu or release cytokines in response to AuTu. However, upon pretreatment of AuTu with IFN-gamma to increase expression of MHC antigens, these T cells regained the ability to recognize and kill AuTu targets. Coincubation of AuTu with the CD4+ or CD8+ T cells significantly augmented expression of class I and II MHC antigens on AuTu. These data indicate that H. saimiri-transformed tumor-reactive T cell lines provide a useful model of interactions between immune effector cells and AuTu, and that CD4+ T cells play a critical role in the regulation of immune responses to squamous cell carcinoma of the head and neck.

Cytotoxicity of histocompatibility leukocyte antigen-DR8-restricted CD4 killer T cells against human autologous squamous cell carcinoma

Although CD8+ killer T cells reacting against human autologous tumor cells have recently been studied in detail, little is known about the cytotoxic mechanism of CD4+ T cells against such tumor cells. In order to investigate this, we have established CD4+ cytotoxic T lymphocyte TcOSC-20 lines. TcOSC-20 showed selective cytotoxic activity against autologous OSC-20 cells, derived from a cancer of the tongue, in an HLA-DR-restricted fashion. HLA-DR8 (DRB1*08032) is the only DR molecule expressed on OSC-20 cells, and anti-DR8 monoclonal antibody could inhibit the cytotoxicity, suggesting that HLA-DRB1*08032 is the tumor rejection antigen-presenting molecule to TcOSC-20. The Fas ligand was expressed on TcOSC-20 lines, and its expression was induced upon mixed lymphocyte-tumor cell culture of autologous peripheral blood lymphocytes. Furthermore, the cytotoxicity of TcOSC-20 was inhibited by anti-Fas ligand antibody. These data imply that TcOSC-20 lines recognize the tumor antigenic peptide presented by HLA-DR8, and exert cytotoxicity against autologous tumor cells via a Fas-mediated cytotoxic pathway.

T-cell recognition of melanoma antigens and its therapeutic applications

During the last few years, tumor immunology has gained impetus due to the molecular definition of T-cell-recognized antigens and the mechanisms of such recognition, antigen processing, and presentation. To date, the majority of the identified melanoma antigens are shared among different melanomas and some are also expressed in tumors of different histology. However, unique antigens expressed solely by the melanoma autologous to the T-cell used for their characterization were also found. The identification of the immunogenic peptides, the minimal target entity required for T-cell recognition, has provided novel reagents for the development of peptide-based immunotherapy. These findings, together with the understanding of requirements for T-lymphocyte recognition and activation, allow the design of new therapeutic protocols. In addition, the large body of data now available on the fine mechanism of antigen processing and presentation have revealed not only the role of the MHC molecules but also that of other intracellular proteins, such as transporter associated with antigen processing-1 and -2 and proteosome-related molecules. These findings suggest that, in order to select patients eligible for vaccination, the expression of the MHC allele involved in T-cell recognition, the profile of tumor antigens, and the status of the antigen-processing system should be carefully evaluated in tumors cells of prospective patients. In this review, some of the basic concepts of immune recognition and the current view of melanoma tumor antigens recognized by T-lymphocytes will be discussed along with the potential application of these findings in designing new therapeutic strategies.

Expression of the co-stimulatory molecule CD40 on melanoma cells

We have previously shown that one of the co-factors required for generation of T-cell responses, B7.1, is variably expressed on melanoma cells. In the present studies we have examined the expression of another important co-factor in T-cell responses, viz., CD40, and investigated regulation of its expression and possible function(s). PCR analysis revealed mRNA for CD40 in all 18 cell lines established from metastatic melanoma and the majority of those from 6 primary melanoma. CD40 protein was detectable in approximately 50% of the cell lines by flow cytometry and in sections from only 2 of 20 melanoma. Expression of CD40 protein was increased in 2 of 3 cell lines with constitutive CD40 expression by interferon-gamma but not by granulocyte/macrophage colony-stimulating factor, interleukin-2 or tumor necrosis factor-alpha. Interaction of monoclonal antibody with CD40 on melanoma cells resulted in an increase in their cell division but did not increase expression of the costimulatory factor B7. Our results suggest that CD40 expression on melanoma may have important effects on their biology. The influence of CD40 expression on T-cell responses to melanoma remains to be investigated.

Melanoma specific Th1 cytotoxic T lymphocyte lines in Vogt-Koyanagi-Harada disease

AIMS/BACKGROUND

To determine the functional properties and cytokine production profiles of melanoma specific cytotoxic T lymphocytes (CTLs) induced from peripheral blood leucocytes of two patients with Vogt-Koyanagi-Harada disease (VKH).

METHODS

Melanoma specific CTL lines were established by long term coculture with a human melanoma cell line (P-36). Cytotoxic activity against P-36 was measured by 51Cr release. The involvement of human leucocyte antigen (HLA) class I or class II molecules in the cytotoxicity of the CTL lines against P-36 was analysed using anti-HLA class I or anti-HLA class II monoclonal antibody (MAb). Surface molecules of CTL lines were analysed by flow cytometry using MAbs specific for CD4, CD8, CD16, CD25, CD56, HLA-DR, T cell antigen receptor (TCR) alpha beta and TCR gamma delta. Cytokine production and soluble interleukin 2 receptor (sIL-2R) secretion were determined by enzyme linked immunosorbent assays. mRNAs of cytokines were analysed using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

CTLs showed strong cytotoxic activity against P-36. The CTL activity of the cell lines against P-36 was inhibited by the anti-HLA-DR MAb, whereas the MAb specific for monomorphic determinants of HLA-A, B, and C failed to block lytic activity. Flow cytometry identified the following surface molecules: CD4+, CD8-, CD16-, CD25+, CD56-, HLA-DR+, TCR alpha beta +, and TCR gamma delta-. CTLs constitutively produced a high level of IL-6. IL-6 production and sIL-2R secretion of CTLs were enhanced when CTLs were stimulated with P-36. CTLs also produced high levels of interferon gamma (IFN-gamma) and IL-2, but not IL-4. mRNAs of IL-2 and IFN-gamma were detected by RT-PCR in the CTLs.

CONCLUSIONS

Melanoma specific HLADR restricted T helper 1 (Th1) CTLs may play a role in the immunopathogenesis of VKH.

Tumor antigens and tumor vaccines: peptides as immunogens

Tumor antigens recognized by human cytotoxic T lymphocytes (CTL) have been identified for multiple types of solid tumors. These include both shared and unique antigens. Unique antigens are those expressed uniquely by one patient's tumor, and shared antigens are those present on tumor cells from many different patients. Many of the shared antigens are derived from tissue-specific differentiation antigens, oncogenes, or a set of antigens expressed only in tumors or in testis. In addition to advances in understanding tumor antigens that stimulate CTL and T-helper cell responses, there have been advances in understanding immunity in general, including the characterization of cytokines, the recognition of the dendritic cell as an optimal antigen-presenting cell (APC), and the characterization of costimulatory molecules as critical components of antigen presentation. Together, these developments have breathed new life into tumor immunology, and they promise to lead to a new generation of peptide- and cell-based tumor vaccines.

Vaccine therapy for cancer

BACKGROUND

Tumor-specific cytotoxic T-lymphocytes (CTLs) can be isolated from the solid tumors, draining lymph nodes, metastatic effusions, and peripheral blood of cancer patients. Despite this evidence for a cell-mediated immune response to cancer, attempts at active specific immunotherapy using cancer vaccines have met with little success in clinical trials.

METHODS

We have reviewed the immunobiology of the cell-mediated immune response to cancer by focusing on what is known about the major histocompatibility complex (MHC)-restricted interaction between tumor cells and CD8+ or CD4+ T-cells. In addition, we review the recent advances in the identification of tumor-associated antigens (TAAs) that are recognized by tumor-specific CTLs in melanoma and other cancers. In discussing these antigens, we highlight the recent identification of several MHC-restricted antigenic peptides that are recognized by CTLs from patients with melanoma and those with ovarian and breast cancer. We examine the implications that the discovery of these TAAs and peptides will have on the development of new anticancer vaccines. We review the most recent vaccine trials in melanoma and other cancers and focus on current concepts aimed at improving the therapeutic efficacy of future vaccines, including genetically engineered tumor cell vaccines.

CONCLUSIONS

With the recent identification of several TAAs and antigenic peptide epitopes in melanoma and other cancers, immunotherapy researchers are now focusing on new strategies for the development of anticancer vaccines. As the repertoire of known TAAs increases and our understanding of the immunobiology of cell-mediated immunity to cancer improves, immunotherapists remain cautiously optimistic in their quest for effective cancer vaccines.

CD4+ Th0 cell clones, isolated from a metastatic lymph node of a melanoma patient, possess cytolytic function

In the present study T lymphocytes isolated from a metastatic lymph node (T-LNL) of a melanoma patient have been cloned. In the attempt to verify whether T-LNL may acquire in vitro functional activities in the absence of tumour-associated antigens, they were cloned utilizing allogenic lymphocytes as feeder cells. Nineteen clones generated from T-LNL proved to be CD4+ and, among these, five were able to kill autologous and allogeneic human melanoma cells in HLA-class-II-restricted way. On the basis of their cytokine production, these CD4+ cytolytic T-LNL clones were shown to belong to the Th0 subset and three of them expressed the V beta 17 chain of the T cell receptor. These results suggest the presence of melanoma-specific but functionally inactive lymphocytes with T cell receptor oligoclonality in the lymph node environment. These specific T cells may acquire in vitro the capacity to kill autologous and allogeneic tumours without any induction by autologous melanoma cells.

HLA class II-restricted recognition of common tumor epitopes on human melanoma cells by CD4+ melanoma-infiltrating lymphocytes

CD4+ T cell clones derived from lymphocytes infiltrating four human melanomas specifically recognized melanoma-derived tumor epitopes as shown by secretion of tumor necrosis factor (TNF) in vitro upon interaction with autologous melanoma cells, whereas they did not recognize HLA class II-expressing autologous lymphoblasts or HLA class II mismatched allogeneic melanoma cells. Specificity was further established by demonstrating that TNF responses to tumor cells were inhibited by HLA-DR or HLA-DQ monoclonal antibodies. Most of these clones cross-reacted with allogeneic melanoma cells expressing a potentially restricting HLA allele or a structurally similar one. These data show that shared epitopes of human melanoma cells presented on HLA class II molecules are frequently recognized by autologous CD4+ T lymphocytes.

Analysis of cytokine secretion by melanoma-specific CD4+ T lymphocytes

Although specific antitumor immune reactivity has been documented extensively in CD8+ T cells derived from melanoma patients, relatively little is known about CD4+ T cell responses against melanoma. Tumor-infiltrating lymphocytes (TIL) cultured from metastatic lesions in five patients yielded cytolytic CD8+ T cells with specific activity against autologous and MHC class I-compatible allogeneic melanoma targets. In four of the five cases studied, CD4+ T cells purified from bulk TIL cultures also reacted specifically with autologous melanoma cells, as manifested by the secretion of various cytokines (GM-CSF, TNF-alpha, and IFN-gamma) after a 24 h cocultivation. Cytokine secretion by CD4+ T cells was MHC class II restricted, and proved to be a more reliable indicator of the immunologic reactivity of CD4+ T cells than cytolysis. Three of the four reactive CD4+ TIL failed to recognize allogeneic melanomas, suggesting recognition of Ag with limited expression in the patient population. Cloning such Ags may provide clues to optimizing current antitumor immunization strategies.

Generation of human-melanoma-specific T lymphocyte clones defining novel cytolytic targets with panels of newly established melanoma cell lines

Melanoma is a cancer where the immune system is believed to play an important role in the control of malignant cell growth. To study the variability of the immune response in melanoma patients, we derived melanoma cell lines from several HLA-A2+ and HLA-A2- patients. The melanoma cell lines studied were designated FM3, FM6, FM9, FM28, FM37, FM45, FM55p, FM55M1 and FM55M2 and were established from eight metastatic tumors as well as from one primary tumor from a total of seven different patients. On the basis of the ability of tumor cells to induce specific cytotoxic T lymphocytes (CTL) from peripheral blood lymphocytes (PBL) in mixed lymphocyte/tumor culture with HLA-A2+ melanoma cells, the FM3 cell line was characterized as highly immunogenic. To investigate the expression of different melanoma-associated antigens recognized by CTL on different melanoma cell lines, we selected the cell line FM3 for restimulation and further T cell cloning experiments. The lytic activity of CTL clones with good proliferative activity was examined using a panel of HLA-A2+ and HLA-A2- melanoma cell lines. None of the tested HLA-A2- melanoma cell lines were susceptible to lysis by the CTL clones, whereas allogeneic HLA-A2+ melanoma cell lines were lysed only by a few CTL clones. On the basis of their reactivity with different melanoma cell lines, it was possible to divide the present CTL clones into at least four groups suggesting the recognition of at least four different antigens. Three of these target structures probably are different from already-described HLA-A2-restricted melanoma-associated antigens, because their expression in the different melanoma cell lines do not correlate with the recognition of melanoma cells by these CTL. The results first indicate that poorly immunogenic melanoma cells may express melanoma-associated antigens, and also suggest that, by using CTL clones obtained against different HLA-class-I-matched melanoma cells, it is possible to define such antigens.

Sigma binding site ligands inhibit cell proliferation in mammary and colon carcinoma cell lines and melanoma cells in culture

Recent evidence suggests a role for sigma (sigma) binding sites in maintenance of cell growth and/or proliferation. The present study examines, for the first time, the effect of sigma binding site ligands on in vitro growth of tumour cells derived from human mammary adenocarcinoma (MCF-7, MDA) and colon carcinoma (LIM 1215, WIDr), and melanoma (Chinnery). Addition of the sigma ligands haloperidol, reduced haloperidol, 1,3-di(2-tolyl)guanidine (DTG), (+)- and (-)-N-allylnormetazocine (SKF 10,047), (+)- and (-)-pentazocine and rimcazole at 6.25, 12.5, 25, 50, 100 microM at the beginning of culture or 24 h later, inhibited cell proliferation in a dose-dependent manner. Light microscopy revealed cell detachment, rounding and cell death. The potency of sigma ligands on melanoma cells was rimcazole > reduced haloperidol > haloperidol = (+)-pentazocine, whereas DTG and (+)- and (-)-SKF 10,047 and (-)-pentazocine had no effect even at 100 microM. In contrast, in MCF-7 cells, rimcazole > reduced haloperidol > haloperidol > (-)-pentazocine > DTG > (+)-pentazocine > (+)-SKF 10,047 > (-)-SKF 10,047. For colon cancer cells, reduced haloperidol > DTG > haloperidol = (-)-pentazocine = (+)-pentazocine = (+)-SKF 10,047. Of all the ligands tested, rimcazole and reduced haloperidol were the most potent inhibitors of cell proliferation. With the exception of one slow-growing colon cancer cell line (LIM 1215), the order of sensitivity of various cell lines to reduced haloperidol, SFK 10,047, DTG, haloperidol and (+)- and (-)-pentazocine was colon carcinoma > mammary adenocarcinoma > melanoma, whereas to rimcazole, the sensitivities of mammary adenocarcinoma and melanoma cells were comparable. The effect of sigma ligands in MCF-7 and melanoma cells was not due to blockade of dopamine D1 and D2 receptors, serotonin (5-HT2) receptors, N-methyl-D-aspartate (NMDA)/phencyclidine receptors, beta-adrenoceptors or opioid receptors, since 100 microM SCH 23390, raclopride, mianserin, (+)-MK-801, propranolol and 1 microM naloxone respectively, were ineffective. However, mianserin and raclopride were inhibitory to melanoma cells and one colon carcinoma cell line, respectively. Taken together, the results are consistent with the recent observation that sigma binding sites may play a role in cell growth and/or cell proliferation.

Direct analysis of tumor-associated peptide antigens

Adoptive immunotherapy with tumor-specific cytotoxic T lymphocytes (CTLs) can induce tumor regressions in animals and in human cancer patients. Antigens recognized by CTLs from cancer patients are being sought as possible immunogens, a number of which have been identified during the past year. The ultimate result may be the development of novel peptide-based immunotherapies and a new understanding of the T-cell response to human cancer.

Human CD4+ T cells specifically recognize a shared melanoma-associated antigen encoded by the tyrosinase gene

Although commonly expressed human melanoma-associated antigens recognized by CD8+ cytolytic T cells have been described, little is known about CD4+ T-cell recognition of melanoma-associated antigens. Epstein-Barr virus-transformed B cells were used to present antigens derived from whole cell lysates of autologous and allogeneic melanomas for recognition by melanoma-specific CD4+ T-cell lines and clones cultured from tumor-infiltrating lymphocytes. HLA-DR-restricted antigens were detected in the lysates on the basis of specific release of cytokines from the responding T cells. Antigen sharing was demonstrated in the majority of melanomas tested, as well as in cultured normal melanocytes, but not in other normal tissues or nonmelanoma tumors. T-cell clones manifested a single recognition pattern, suggesting the presence of an immunodominant epitope. This epitope was identified as a product of the tyrosinase gene, which has also been shown to encode class I-restricted epitopes recognized by CD8+ T cells from melanoma patients. Identification of commonly expressed tumor-associated protein molecules containing epitopes presented by both class I and class II major histocompatibility molecules may provide optimal reagents for cancer immunization strategies.

Characterization and augmentation of CD4+ cytotoxic T cell lines against melanoma

Cytotoxic T cells have been implicated in the control of the progression of human melanoma. Most studies on human tumor T cell immunity have focused on the CD3+CD8+ cytotoxic T lymphocyte (CTL) phenotype; however, CD3+CD4+ CTL are important effector cells in other diseases and may also contribute to antimelanoma immunity. In this study we compared the functional activity of CD3+CD4+ and CD3+CD8+ CTL lines generated against autologous melanoma cells. CD8+ CTL had twofold higher cytotoxicity and serine esterase activity than CD4+ CTL. CD8+ CTL also were better binders to autologous melanoma cells. Binding of both CD4+ and CD8+ CTL to melanoma cells was significantly inhibited by ICAM-1 mAb. Interleukin-2 (IL-2) and IL-4 secretion was induced in both CD4+ and CD8+ CTL after stimulation by melanoma cells. A reverse transcriptase polymerase chain reaction performed on specific messenger RNA showed that both CD4+ and CD8+ CTL expressed IL-1, IL-2 and IL-4; CD4+ CTL also expressed interferon gamma (IFN). Both CTL phenotypes expressed receptors for IL-2 and IFN but only CD4+ CTL expressed the receptor for IL-4. Methods to augment CD4+ CTL growth were assessed using different combinations of cytokines. The combination of IL-2, IL-4 and IFN provided the optimal stimulation. Treatment of melanoma target cells with IL-4 and IFN enhanced CD4+ CTL recognition activity. CD4+ T cells are associated with antigen memory response and helper function, therefore activation of CD4+ CTL may be more beneficial with respect to long-term protective antimelanoma immunity.

Expression of the co-stimulatory molecule B7 on melanoma cells

The induction of T-cell responses against tumor cells is believed to depend on both recognition of antigen and receipt of co-stimulatory signals from interaction of ligands such as B7 with its receptors CD28 or CTLA-4 on T cells. In the present study the expression of B7 on cultured human melanoma cells was studied at the mRNA level by reverse PCR analysis and surface expression by flow cytometric analysis with monoclonal antibodies (MAbs). PCR analysis revealed mRNA for B7 in 3 of 6 (50%) cultured primary melanoma and 8 of 19 (42%) cultures of metastatic melanoma. Analysis of B7 expression by flow cytometry using the BB1 MAb revealed low levels of expression in 3 of 10 melanoma that had mRNA for B7. In 2 of the latter (but not 4 other PCR+ lines) expression could be increased by culture in GM-CSF, IL-2, IFN-gamma and IFN-alpha 2. Our results indicate that although mRNA for B7 is present in 40-50% of melanoma cell lines, expression at the protein level is at low or undetectable levels in the majority of the cell lines. Expression of B7 protein was also not detected in studies on tissue sections from 11 primary and 9 metastatic melanomas.

Frequency of cytotoxic T lymphocyte precursors (CTLp) interacting with autologous tumor via the T-cell receptor: limiting dilution analysis of specific CTLp in peripheral blood and tumor-invaded lymph nodes of melanoma patients

The frequencies of cytotoxic T-lymphocyte precursors (CTLp) that lyse autologous tumor by a T-cell receptor (TCR)-dependent mechanism (specific CTLp) were evaluated by limiting dilution analysis (LDA) using lymphocytes from peripheral blood (PBL) and from surgically resected, tumor-invaded lymph nodes (LNL) in 9 melanoma patients. The frequency of specific CTLp was determined in PBLs and/or LNIs of all patients by a modified LDA assay, enabling us to measure lytic activity on the autologous tumor that could be significantly inhibited by an anti-CD3 monoclonal antibody (MAb). This assay allowed us to detect frequencies of specific CTLp ranging from 1/720 to 1/32,037 in peripheral blood and from 1/328 to 1/22,061 in tumor-invaded lymph nodes. These frequencies indicated that lymphoid populations from PBLs or LNLs of melanoma patients may contain as low as 30 to as much as 3,000 specific CTLp/10(6) lymphocytes. In addition, comparison of wells containing specific CTLp with those showing no inhibition by anti-CD3 MAb indicated that specific CTLp represent between 3 and 88% of all precursors with lytic activity on the tumor. In 6 of 9 patients, no marked differences between PBLs and LNIs in specific CTLp frequencies were found. A 10-fold increase of specific CTLp, in comparison to PBL and LNL, was found only in lymphocytes isolated from a subcutaneous metastasis of one patient. Our results indicate that CTLp interacting with autologous tumor by a TCR-dependent mechanism exist in PBL and LNL of most melanoma patients, although a wide variation in their absolute number is evident among different patients.

Melanoma-specific CD4+ T lymphocytes recognize human melanoma antigens processed and presented by Epstein-Barr virus-transformed B cells

While much emphasis has been placed on the role of MHC class I-restricted CD8+ T cells in the recognition of tumor-specific antigens (Ag), evidence has accumulated that CD4+ T cells also play a critical role in the anti-tumor immune response. However, little information exists on the nature of MHC class II-restricted human tumor Ag. In an attempt to develop in vitro systems to characterize such Ag, we examined the ability of Epstein-Barr virus (EBV)-transformed B cells to present melanoma-associated Ag to melanoma-specific CD4+ cells. CD4+ T cells cultured from lymphocytes infiltrating a s.c. melanoma metastasis secreted TNF-alpha and GM-CSF specifically in response to autologous cultured melanoma cells expressing MHC class II molecules. These CD4+ cells also recognized MHC class II-compatible EBV-B cells pulsed with extracts of autologous melanoma cells, but failed to recognize EBV-B cells pulsed with autologous non-transformed cells or a variety of allogeneic tumors or normal cells. B cells pre-fixed with paraformaldehyde were incapable of Ag presentation, suggesting that intracellular processing events were occurring. Antibody-blocking studies defined HLA-DR as the dominant if not exclusive restriction locus in this T-B interaction, and HLA-DR genotyping revealed DRBI*0404 to be the probable restriction element. In a second patient, a CD4+ T-cell clone cultured from a melanoma lesion recognized autologous tumor Ag presented by autologous EBV-B; no corss-reactivity was observed with the other tumor system investigated, nor with autologous CD4+ T cells specific for tetanus toxoid. These findings demonstrate that tumor Ag can be processed and presented by EBV-transformed B cells to MHC class II-restricted tumor-specific CD4+ T cells. They also provide a model system for direct identification of these tumor-derived antigens.

T cell recognition of melanoma antigens in association with HLA-A1 on allogeneic melanoma cells

Previous studies have shown that recognition of melanoma by cytotoxic T lymphocytes may be restricted by HLA-A1, A2 and other HLA antigens. The present study examined the cytotoxic specificity and major histocompatibility complex restriction of cloned cytotoxic T lymphocytes (CTL) isolated from a patient with the HLA phenotype A3,31 who had been immunized with a vaccine prepared from HLA-A1,3 melanoma cells. Cytotoxic assays against HLA-typed allogeneic melanoma cells indicated that cloned CTL from the patient were able to kill allogeneic melanoma cells expressing HLA-A1 but not other HLA-A1-positive cells. Studies on a representative clone indicated that proliferation and cytokine (tumour necrosis factor alpha) production in response to melanoma cells was also associated with HLA-A1 on melanoma cells. Response to the melanoma cells was associated with interleukin-4 (IL-4) rather than IL-2 production. The antigen recognized in the context of HLA-A1 on allogeneic melanoma cells was detected in cytotoxic assays on cells from 9 of 12 HLA-A1+ melanoma cell lines and did not appear to be the product of the MAGE-1 or -3 genes. These findings suggest that T cells can recognize melanoma antigens in the context of alloantigens and that allogeneic vaccines containing "immunodominant" alloantigens may generate CTL that are ineffective against autologous melanoma. The study does not, however, exclude the possibility that CTL with specificity to the latter may be activated by allogeneic vaccines, and further studies are needed to answer this question.

Isolation and characterization of the intracellular MHC class II compartment

An intracellular compartment has been isolated to which MHC class II molecules are transported on their way to the plasma membrane. They arrive with an associated invariant chain which is then proteolytically processed while MHC class II molecules acquire antigenic peptide. These loaded class II molecules then leave the compartment devoid of invariant chain and bound for the plasma membrane. This compartment represents a new stage in the endocytic/lysosomal pathway.

Identification of a peptide recognized by five melanoma-specific human cytotoxic T cell lines

Of several thousand peptides presented by the major histocompatibility molecule HLA-A2.1, at least nine are recognized by melanoma-specific cytotoxic T lymphocytes (CTLs). Tandem mass spectrometry was used to identify and to sequence one of these peptide epitopes. Melanoma-specific CTLs had an exceptionally high affinity for this nine-residue peptide, which reconstituted an epitope for CTL lines from each of five different melanoma patients tested. Recognition by multiple CTL lines suggests that this may be a promising candidate for use in peptide-based melanoma vaccines.

Tumor-rejection antigens recognized by T lymphocytes

Generations of immunologists have been searching for evidence to confirm the tantalizing notion that tumor-rejection antigens exist. If found, the ultimate reward was the possibility that these molecules might be used to induce tumor-specific immunity and effect tumor rejection. Until recently rewards have been few and far between. That is changing. The immediate rewards have become more satisfying and the ultimate reward almost palpable.

Expression of the neuroglandular antigen and analogues in melanoma. CD9 expression appears inversely related to metastatic potential of melanoma

Immunohistological methods were used to examine the relation between the metastatic potential of melanoma and expression of the neuroglandular antigen (CD63) and other members of this family of molecules, CD53, CD37, CD9 and the target of an anti-proliferative antibody (TAPA-I), as well as MHC-class-I and -II antigens. The criteria used to establish metastatic potential were their relation to thickness of the primary melanoma, and differences in expression between vertical and radial growth phases of primary melanoma and between primary and metastatic melanoma. Studies on basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) were also included as controls for malignant skin cancers with low metastatic potential. Expression of CD9 and MHC-class-I antigen was found to be inversely related to thickness of the primary tumor, and CD9 was expressed predominantly on primary rather than on metastatic tumors. CD9 expression correlated with MHC-class-I expression on melanoma, and both were expressed on BCCs and SCCs having low metastatic potential, but not on compound nevi. CD63 and TAPA-I were expressed on nevi but not on SCC and BCC. Leu 13 is a molecule associated with TAPA-I in lymphomas, and was found to be expressed in sections from 5 out of 34 primary and 5 out of 21 metastatic melanoma. CD53 and CD37 were not detected on melanoma. Our results indicate that several members of the neuroglandular antigen are expressed in melanoma and that low expression of CD9 on primary melanomas might have prognostic significance with respect to the potential for metastasis.