Immunogenicity and immunosensitivity of ex vivo human carcinomas: interferon gamma and tumour necrosis factor alpha treatment of tumour cells potentiates their interaction with autologous blood lymphocytes

Immuno-gene therapy of melanoma by tumor antigen epitope modified IFN-gamma

Cytokine-based vaccines play a major part in tumor immuno-gene therapy. However, down-regulated antigen expression on tumor cells may diminish the immuno-potentiating aspects of cellular vaccines. In this study, we coexpressed a tumor antigen epitope with IFN-gamma in the same gene by replacing the IFN-gamma signal peptide with an antigen epitope-expressing signal peptide. We then investigated the effect of the antigen epitope-incorporated IFN-gamma on the immunotherapy of murine melanoma B16 tumors. Results showed that TRP-2 epitope-expressing IFN-gamma decreased B16 tumorigenicity and enhanced its immunogenicity after gene transfer. Protective immunity against wild type B16 tumors was induced by vaccination with IFN-gamma transiently gene-modified tumor cells. These data suggest that cellular vaccines engineered to express an antigen epitope within an immunostimulatory cytokine could potentiate the immunization effect.

Interferon-gamma-induced ICAM-1 and CD40 expression, complete lack of HLA-DR and CD80 (B7.1), and inconsistent HLA-ABC expression in basal cell carcinoma: a possible role for interleukin-10?

Basal cell carcinomas (BCCs) of the skin show varying degrees of peritumoural inflammatory infiltrate consisting mainly of T cells, but lack an effective T-cell-mediated immune response. This may be caused by the absence of the major histocompatibility complex (MHC) class I and II antigens, intercellular adhesion molecule-1 (ICAM-1), CD40 and CD80 (B7.1). Interferon-gamma (IFN-gamma) is known to induce or up-regulate their expression on epithelial cells, whereas interleukin-10 (IL-10) down-regulates their expression. The induction and up-regulation of HLA-ABC, HLA-DR, ICAM-1, CD40, and CD80 in BCC and normal skin from BCC patients were investigated in a culture system using recombinant human IFN-gamma (rHuIFN-gamma). The levels of IL-10 were determined in the supernatants after culture. The results showed that only ICAM-1 expression was significantly up-regulated on BCC cells. However, in the normal epidermis of BCC patients and in the epidermis overlying the tumour nests, significant up-regulation of ICAM-1, and CD40, and CD80 and slight up-regulation of HLA-DR were observed. No changes in HLA-ABC expression were observed in either normal skin or BCC. High levels of IL-10 were present in the supernatants of BCC biopsies after culture. It may be concluded that it is highly likely that the presence of IL-10 in BCC is directly or indirectly responsible for the complete lack of expression of HLA-DR, ICAM-1, CD40 and CD80 and the inconsistent expression of HLA-ABC on BCC cells in situ and may be a way of escaping immune survillance.

Tumor surveillance: expression of the transporter associated with antigen processing (TAP-1) in ex-vivo human tumor samples and its elevation by in vitro treatment with IFN-gamma and TNF-alpha

We have analyzed 30 human tumor specimens (two breast, six lung, and 21 ovarian carcinomas and one malignant melanoma) for the expression of the transporter associated with antigen processing, TAP-1. Cell suspensions judged to contain negligible contamination with non-tumor cells were tested for reactivity with the antibody directed to TAP-1 in Western blot. According to these results all lysates prepared from the tumor samples contained the protein, but with considerable quantitative variations. Tumors exposed in vitro for a short time to IFN-gamma and TNF-alpha had elevated TAP-1 levels in 12 out of 30 experiments. In accordance with previous results, the tumor cell populations were heterogeneous with regard to MHC class I expression, as analyzed by indirect immunofluorescence on viable cell suspensions. Short term in vitro treatment with IFN-gamma and TNF-alpha elevated MHC class I expression in several tumors. In several mixed cultures, cytokine treated tumor cells induced cytotoxic activity in autologous or allogeneic lymphocyte populations. In vitro treatment with IFN-gamma and TNF-alpha upregulated thus the expression of MHC class I and TAP-1 in a fraction of the tumor samples. However the potentiation of the capacity to interact with T cells induced by the cytokines was not always parallel with the changes in these two parameters. It is therefore likely that the cytokine treatment induced additional changes in the tumors which contributed to their capacity to elicit the T cell response.

Expression of interferon-gamma receptors and interferon-gamma-induced up-regulation of intercellular adhesion molecule-1 in basal cell carcinoma; decreased expression of IFN-gamma R and shedding of ICAM-1 as a means to escape immune surveillance

The peritumoural inflammatory infiltrate in basal cell carcinoma (BCC) of the skin consists mainly of T lymphocytes which hardly invade the tumour nests. The absence of intercellular adhesion molecule-1 (ICAM-1) on BCC cells may explain the lack of tumour-infiltrating cells and the lack of an active cell-mediated immune response in this tumour. In this study, the induction of ICAM-1 was investigated in BCC biopsies using recombinant human interferon-gamma (rHuIFN-gamma). The expression of interferon-gamma receptors (IFN-gamma R) in the biopsies was also investigated. The results showed that BCC cells expressed ICAM-1 after incubation with rHuIFN-gamma, but to a lesser degree than normal epidermal cells. The levels of shed ICAM-1 were significantly increased in the culture supernatants of tumour biopsies compared with those from normal skin biopsies, after culturing in the presence of rHuIFN-gamma. The expression of IFN-gamma R was significantly decreased on the tumour cells compared with the overlying epidermis. The decreased expression of IFN-gamma R on the tumour cells and the shedding of ICAM-1 into the peritumoural stroma may be a plausible mechanism by which the tumour cells are protected against an active cell-mediated immune response.

The allogeneic CD4+ T-cell-mediated graft-versus-leukemia effect

CD4+ T-cells have emerged as important cells in the initiation and delivery of the GVL response. Nevertheless it seems likely that they act in concert with other T-cells and NK cell effectors to produce the full in vivo effect of GVL. How they interact with other effectors is yet to be determined. Furthermore it is very likely that different hematological malignancies have different susceptibility to attack by various lymphocyte subsets, depending upon their MHC expression, nature of the antigens presented and other properties not yet defined. Here we specifically focus on the role of CD4+ T-cells in mediating GVL, particularly in chronic myeloid leukemia. Candidate antigens recognised by CD4+ cells are described and new approaches to GVL modulation in clinical bone marrow transplantation are discussed.

Auto-tumor reactive cytotoxic T-cell responses in B-cell non-Hodgkin's lymphoma

We have generated cytotoxic T-lymphocytes (CTLs) from the peripheral blood (PB) of eight B-cell non-Hodgkin's lymphoma (NHL) patients by in vitro coculture with autologous fresh tumor cells. Their functional activity was assessed in 51Cr release assay and was found to be MHC class I restricted. Our results indicate the presence of T-cells cytotoxic for autologous tumor cells in the PB of these patients but these were relatively small numbers in small lymphocytic lymphomas (SLLs). Treatment of fresh tumor cells with rIFN-gamma and rTNF-alpha alone, or in combination significantly increased their susceptibility in 4/5 cases of SLLs, and a case of diffuse large cell lymphoma and Burkitt lymphoma (BL), while, B-cell lymphoma, rich in T-cells, did not show any appreciable increase. Fresh tumor cells were also analysed for MHC class I and ICAM-1 antigens by flow cytometry, in 5/8 cases before and after cytokine treatment. Significant upregulation of MHC class I antigens but with no detectable change in ICAM-1 observed in a case of SLL and BL, correlated with enhanced susceptibility. These findings suggest the possible role of MHC class I antigens in the cytotoxic susceptibility of autologous tumor cells in B-cell NHL.

An immunohistochemical study of altered immunomodulatory molecule expression in head and neck squamous cell carcinoma

For the presentation of peptide antigens to cytotoxic CD8+ T lymphocytes of the immune system, the expression of human leukocyte antigen (HLA) class I molecules on the cell surface is necessary. There is increasing evidence that surface HLA class I antigen expression is altered in a variety of human tumours by either loss or down-regulation of these molecules, which may be a strategy for evasion of immunosurveillance by malignant cells. This study has examined the expression of HLA class I molecules in head and neck squamous cell carcinoma (HNSCC) specimens by immunohistochemistry, using a wide panel of antibodies directed against allele-specific as well as monomorphic determinants of these molecules. The expression of TAP proteins, HLA-DR and the co-stimulatory molecule ICAM-1 were also studied. In addition, the expression of the tumour-associated antigens (TAA) p53 and MAGE genes was determined. Aberrant allelic expression of HLA class I antigens was detected in 17 out of 34 (50%) of the specimens stained, whereas HLA class I expression determined by W6/32 staining was found to be heterogeneous in only 2 out of 34 (6%) cases. Decreased expression of ICAM-1 was observed in 12 out of 34 (35%) tumour specimens and de novo expression of HLA-DR (HLA class II) by carcinoma cells in 13 out of 34 (38%) cases. Aberrant expression of HLA class I antigens was frequently observed in cases in which MAGE genes and p53 overexpression were detected. The altered expression of these immunomodulatory molecules in HNSCC may affect prognosis and has important implications for peptide-based immunotherapy strategies for these patients.

Interferon-gamma and tumor necrosis factor-alpha treatment of ex vivo human carcinoma cells potentiates their interaction with allogeneic lymphocytes

Short-term exposure of ex vivo carcinoma and sarcoma cells to IFN-gamma and TNF-alpha induced or elevated to detectable levels the surface expression of MHC class I, class II, and ICAM-1 (CD54), but only rarely the B7 (CD80) molecules. The cytokine-treated tumor cells interacted more efficiently with allogeneic blood lymphocytes collected from healthy donors compared with untreated cells. This was demonstrated (1) by the induction of DNA synthesis and generation of cytotoxic activity in mixed cultures and (2) by the elevated susceptibility to the cytotoxic effectors. Although the cytokine-induced increase in MHC and ICAM-1 on the low-expressor tumors were probably important to the interaction with lymphocytes, it is likely that other properties were also induced that contributed to the phenomenon. This was indicated by the results obtained with several tumors that expressed indigenously high levels of these molecules but reacted with the allogeneic lymphocytes only or more efficiently after treatment with IFN-gamma and TNF-alpha. In these experiments B7 expression did not influence the efficiency of interactions between lymphocyte and tumor cells. The results also showed that, under the conditions used, the untreated tumor cells that did not activate allogeneic lymphocytes were sensitive to appropriately activated effectors. Thus the afferent and efferent arms of lymphocyte-tumor cell interactions appeared to have different requirements.