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

Anti-vascular endothelial growth factor receptor (VEGFR) 2 autoantibody identification in glioblastoma patient using single B cell-based antibody gene cloning

Antibody direct cloning from single B cells is simple and efficient and has been successful in antibody identification of infectious diseases. However, although a recent whole-exome sequencing revealed abundant heterogeneic mutation accumulation in cancers, identification and synthesis of autoantibodies against specific cancer-associated antigens is still difficult in cancer patients owing to the very small number of B cells producing autoantibodies. In the present study, to identify autoantibodies targeting tumor antigens, we measured the titer of autoantibodies in high-grade glioma patients' plasma and identified two patients with elevated autoantibodies to a few transmembrane proteins. Specific B cells producing autoantibody against vascular endothelial growth factor receptor (VEGFR) 2 were immunostained with labeled protein and anti-human IgG antibody, and then collected by a single cell sorter. Finally, 22 antibody genes were successfully identified using direct IgG cloning from single B cell mRNA, and two antibody clones were found to have significant VEGFR2-specific binding affinity. The current direct human IgG gene cloning technique for identifying human antibodies derived from IgG-memory B cells avoids time-consuming procedures such as phage display-based antibody-library screening, and therefore may be applicable to identifying human autoantibodies in a variety of disorders including cancers even when antibody elevation is not detected because of a very small number of memory B cells.

Identification and characterization of myeloma-associated antigens in Trichinella spiralis

To investigate the presence of myeloma-associated antigens in Trichinella spiralis and their anti-tumor effect, cross-immune responses between antigens of the myeloma cell SP2/0 versus positive sera to T. spiralis, and antigens of T. spiralis versus positive sera to myeloma cell SP2/0 were determined using T. spiralis and myeloma specific enzyme-linked immunosorbent assays (ELISA). The myeloma-associated antigens in T. spiralis were separated by ultrafiltration and 2-D electrophoresis, and the amino acid sequences and molecular weights were determined by spectrometry. An obvious reaction was found between a 33 kDa antigen and positive sera, and the major component of the antigen was tropomyosin (TM), which is an surface acidic protein with 284 amino acids. Mice were immunized with TM to determine the anti-tumor effect in vivo. The results showed that CD4(+), CD8(+) T lymphocyte, and CD19(+) B lymphocyte were significantly increased (P<0.05). The anti-tumor effects were significantly different between mice immunized with the antigens or adjuvant alone (P<0.05), while the difference between mice immunized with antigens and whole T. spiralis was not significant (P>0.05). The results indicated that TM identified in this study may play a role in eliciting cross-protective immunity.

Shared MHC class II-dependent melanoma ribosomal protein L8 identified by phage display

Antigens recognized by T helper (Th) cells in the context of MHC class II molecules have vaccine potential against cancer and infectious agents. We have described previously a melanoma patient's HLA-DR7-restricted Th cell clone recognizing an antigen, which is shared among melanoma and glioma cells derived from various patients. Here, this antigen was cloned using a novel antigen phage display approach. The antigen was identified as the ribosomal protein L8 (RPL8). A peptide of RPL8 significantly stimulated proliferation and/or cytokine expression of the Th cell clone and lymphocytes in four of nine HLA-DR7(+) melanoma patients but not in healthy volunteers. The RPL8 antigen may represent a relevant vaccine target for patients with melanoma, glioma, and breast carcinoma whose tumors express this protein.

A CD4+, HLA-DR7-restricted T-helper lymphocyte clone recognizes an antigen shared by human malignant melanoma and glioma

CD4(+) Th cells that are restricted by MHC class II molecules play an important role in the induction of antitumor immune responses. We have established a stable CD4(+) Th cell clone (Th35-1A) from the PBMCs of a patient with primary cutaneous melanoma. The Th cell clone is noncytolytic and proliferates specifically in the presence of irradiated autologous melanoma cells or autologous EBV-transformed B cells pulsed with melanoma tumor cell lysates. Th35-1A produces IFN-gamma (a Th1-type cytokine) after autologous tumor cell stimulation, and its proliferative reactivity is HLA class II-restricted. Th cells showed helper activity for PWM responses of PBMCs. Using a panel of HLA class II-matched and unmatched EBV-B cells as APCs and allogeneic melanoma tumor cell lysate as stimulant, DR7 was delineated as the HLA class II restriction element used by the Th cell clone. In agreement with these results, transfection of an allogeneic melanoma cell line with HLA-DR7 isolated from autologous EBV-B cells rendered the cell line stimulatory for Th35-1A cells. Specificity studies using autologous EBV-B cells (EBV-B35) pulsed with a panel of allogeneic tumor cell lysates of various tissue origins indicated that the Th cell clone recognizes an antigen shared by melanoma and glioma cells. The availability of the Th cell clone may lead to the development of new therapies against melanoma, using adoptive Th cell transfer and/or active immunization with a shared Th cell antigen.

Generation of melanoma-specific, cytotoxic CD4(+) T helper 2 cells: requirement of both HLA-DR15 and Fas antigens on melanomas for their lysis by Th2 cells

Recognition of melanoma antigens by HLA class-II-restricted CD4(+) T lymphocytes has been investigated. Two cytotoxic CD4(+) T cell lines were established by stimulating PBLs from a melanoma patient with either parental or IFN-gamma-transduced autologous tumor cells. These T cells secreted IL-4, but not IL-2, IFN-gamma, or TNF-beta, in response to the autologous melanoma cells, suggesting that they belong to the Th2 subtype. Their cytotoxicity was directed against the IFN-gamma-transduced melanoma cells and was HLA-DR-restricted. The autologous and two allogeneic IFN-gamma-modified melanoma cell lines shared melanoma antigen(s) presented in the context of HLA-DR15. HLA-DR15(+) nonmelanoma cells were resistant targets indicating that the shared antigen(s) is melanoma associated. Parental autologous and HLA-DR-matched allogeneic melanoma cell lines, displaying low levels of HLA-DR antigens, induced Th2 proliferation and cytokine release, but were insensitive to lysis prior to upregulation of HLA-DR and Fas antigens by IFN-gamma. Cytolysis was inhibited by anti-HLA-DR and by anti-Fas antibodies, suggesting that the cytolysis is mediated via the Fas pathway. While small amounts of HLA-DR15 molecules on melanoma cells are sufficient for Th2 proliferation and cytokine release, higher amounts of HLA-DR15 and the expression of Fas are required for CD4(+)-mediated lysis.

Tumorigenicity and immunogenicity of murine tumor cells expressing an MHC class II molecule with a covalently bound antigenic peptide

The significance of CD4+ lymphocytes and major histocompatibility complex (MHC) class II-restricted antigens in antitumor immunity has been demonstrated in several animal models as well as in some human tumors. However, because of the lack of known class II-restricted antigens, the participation of CD4+ cells in antitumor responses has not been well characterized. Recent reports showed that class II proteins covalently linked to an antigenic peptide could be constructed and cells expressing these fusion proteins were recognized by specific TH cells. The aim of this study was to determine the effect of the expression of a class II-peptide construct on the tumorigenicity and immunogenicity of transfected murine tumor cells. We have constructed a gene for I-Ed beta chain covalently coupled to the I-Ed-restricted TH cell determinant of sperm whale myoglobin (SWM132-145). This class II fusion protein was recognized by a specific TH cell line on the surface of COS-7 cells or BALB/c sarcoma cells. The sarcoma cells expressing the MHC-peptide complex were rejected by immunocompetent BALB/c mice, and in vivo T-cell subset depletion experiments suggested the importance of CD4+ cells in the rejection. Moreover, splenocytes from mice immunized with tumor cells expressing the I-Ed-SWM complex showed specific peptide recognition in vitro. Such covalent MHC-peptide complexes could prove useful in studies on the role of CD4+ lymphocytes in antitumor immune responses, and also in designing new, more effective vaccine approaches to the immunotherapy of cancer, as class II-restricted tumor-associated antigens are identified for human cancers.

Presence of activated lymphocytes in the peripheral blood of patients with halo nevi

BACKGROUND

The involution of the central pigmented lesion in halo nevus (HN) seems to be mediated by an immune response against self antigens expressed by melanocytes.

OBJECTIVE

We assessed the presence of activated lymphocytes in the peripheral blood lymphocytes from patients with HN.

METHODS

Peripheral blood was obtained from patients with HN associated with benign pigmented lesions (5) or melanoma (2) as well as from patients with melanoma without HN (5) and healthy subjects (10). Activated lymphocytes were detected by flow cytometry analysis using monoclonal antibodies (mAb) against CD69, CD71, CD98, HLA-DR, and activated beta(1) integrins (HUTS-21 mAb).

RESULTS

The peripheral blood lymphocytes from patients with HN, associated with either benign or malignant lesions, exhibited a significantly higher expression of all activation markers studied compared with patients with melanoma without HN or compared with healthy subjects. Therefore the peripheral blood of HN patients contained a significant fraction of lymphocytes with an activated (CD69(+), HLA-DR(+), CD98(bright)), cell proliferating (CD71( bright)), and high adhesive (HUTS-21(bright)) phenotype. These activated cells disappeared from peripheral blood after the surgical resection of the skin lesion.

CONCLUSION

Our findings further support the involvement of immune activation in HN phenomenon.

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.

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.

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.

A B7-1-transfected human melanoma line stimulates proliferation and cytotoxicity of autologous and allogeneic lymphocytes

B7 co-stimulation is necessary to activate resting T cells upon antigen recognition by the T cell receptor. To see whether expression of B7 may render human melanoma cells able to stimulate T cells, a cloned melanoma line (Me1B6), which did not express B7-1, was transfected with the human B7-1 gene. In proliferation assays, B7-1 transfected cells (Me1B6/B7) showed greater stimulatory activity of allogeneic and autologous peripheral blood lymphocytes (PBL) compared to parental, non-transfected tumor cells. This effect was also seen when allogeneic CD8+ and CD4+ subpopulations were used as effectors. In these studies, activation of lymphocytes was B7-1-dependent and HLA classes I and II mediated. The higher proliferation correlated with an increased lytic activity by PBL stimulated with B7-1+ tumor cells against the untransfected Me1B6. Furthermore, PBL from a metastatic melanoma patient stimulated by Me1B6/B7 developed an higher lytic activity not only against Me1B6 but also against their autologous, B7-1- tumor. Finally, after Me1B6/B7 stimulation, PBL released interleukin (IL)-2 and interferon-gamma, but not IL-4, suggesting a Th1-mediated response. These data support the use of B7-1 transfected melanoma cells in the therapeutic vaccination of melanoma patients.

The role of CD4+ tumor-infiltrating lymphocytes in human solid tumors

Many, if not all, solid tumors are characterized by a T cell infiltrate, usually consisting of CD4+ and CD8+ T cells. Characterization of both subsets of tumor-infiltrating lymphocytes (TIL) have shown that each population can be divided into tumor-specific and tumor-nonspecific T cells. A small proportion of tumor-specific CD4+ TIL can directly lyse tumor cells in an HLA class I- or II-restricted fashion. The majority of tumor-specific CD4+ TIL, however, recognize tumor antigens presented on HLA class II molecules by antigen-presenting cells (APC). At the same time, APC in the tumor environment express elevated levels of heat shock antigen (Hsp) 70 (and perhaps other antigens) that can be specifically recognized by tumor-nonspecific CD4+ TIL when presented by HLA class II. Functionally, CD4+ T cells can be distinguished into Th0 (production of IL-2, IL-4, and IFN-gamma), Th1 (IL-2 and IFN-gamma), and Th2 (IL-4). In addition, stressed CD4+ TIL have the ability to produce the growth factors heparin binding epidermal growth factor and basic fibroblast growth factor that support tumor growth. Since the efficacy of an antitumor immune response is codetermined by the net effect of stimulatory and inhibitory cytokines, a detailed understanding of the developmental pathways of CD4+ TIL subsets and their interactions is critical for the design of clinical protocols.

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.

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.

Expression of transcripts for two interleukin 8 receptors in human phagocytes, lymphocytes and melanoma cells

Two cDNAs coding for distinct interleukin 8 (IL-8) receptors, IL-8R1 [Murphy and Tiffany (1991) Science 253, 1280-1283] and IL-8R2 [Holmes, Lee, Kuang, Rice and Wood (1991) Science 253, 1278-1280] have been reported, and biochemical studies on human neutrophils have revealed two proteins (p70 and p44) that bind IL-8 with high affinity [Moser, Schumacher, von Tscharner, Clark-Lewis and Baggiolini (1991), J. Biol. Chem. 266, 10666-10671]. We have cloned the cDNA coding for IL-8R1 from a library of differentiated HL-60 cells. Transfection of this cDNA into Jurkat cells resulted in the expression of high-affinity binding for IL-8 and two related cytokines, GRO alpha and neutrophil-activating peptide 2 (Kd 0.5-1.0 nM). Northern-blot analysis with the IL-8R1 cDNA as probe revealed abundant expression of transcripts of different size in human neutrophils and low-level expression of a single RNA species in HL-60 cells differentiated with dimethyl sulphoxide and retinoic acid. Because of the extensive nucleotide sequence similarity of the cDNAs for IL-8R1 and IL-8R2, the reverse-transcription PCR method was used for analysis of RNA expression in myeloid and lymphoid cells, 19 cell lines established from human primary melanomas or metastases, two melanocyte and one fibroblast cell lines. IL-8R1 mRNA transcripts were expressed at high levels in neutrophils, and to a lesser extent in blood monocytes and the myeloid cell lines, HL-60 and AML 193, but were not found in THP-1 cells, lymphocytes and Jurkat cells. IL-8R2 mRNA transcripts, by contrast, were found in all blood cells and related cell lines, as well as in all melanoma, melanocyte and fibroblast cell lines tested. As for IL-8R1, IL-8R2 mRNA expression was highest in neutrophils. These results suggest that IL-8R1 and IL-8R2 may both be involved in neutrophil activation by IL-8 and related cytokines, and presumably correspond to p70 and p44, the receptors that were identified biochemically. Possible IL-8 functions on lymphocytes and melanoma cells, e.g. chemotaxis and proliferation, must be independent of IL-8R1 and may be mediated by IL-8R2.