Ingegerd Hellström

Costimulation of antitumor immunity by the B7 counterreceptor for the T lymphocyte molecules CD28 and CTLA-4

Interaction of the B7 molecule on antigen-presenting cells with its receptors CD28 and CTLA-4 on T cells provides costimulatory signals for T cell activation. We have studied the effects of B7 on antitumor immunity to a murine melanoma that expresses a rejection antigen associated with the E7 gene product of human papillomavirus 16. While this E7+ tumor grows progressively in immunocompetent hosts, cotransfection of its cells with B7 led to tumor regression by a B7-dependent immune response mediated by CD8+ cytolytic T lymphocytes. The immune response induced by E7+B7+ tumor cells also caused regression of E7+B7- tumors at distant sites and was curative for established E7+B7- micrometastases. Our findings suggest that increasing T cell costimulation through the CD28 and CTLA-4 receptors may have therapeutic usefulness for generating immunity against tumors expressing viral antigens.

Lymphocyte-mediated cytotoxicity and blocking serum activity to tumor antigens.

Publisher Summary This chapter reviews the evidence for cell-mediated immune reactions against tumors in animals and man, particularly, the reactions that can lead to destruction of neoplastic cells cultivated in vitro. Various mechanisms by which tumor cells can escape from immunological destruction have been discussed, most notably one involving blocking factors, present in the serum. Findings analogous to those obtained when studying tumor immunity (coexistence of cell-mediated reactivity and blocking serum activity) have been summarized from three other areas (pregnancy, allografting, and chimeras). The studies reviewed in the chapter have given a relatively large amount of evidence for various cell-mediated and humoral immunological reactions against growing tumors, and at least some of the reactions observed in vitro appear to be able to influence tumor growth in vivo .

Mesothelin-family proteins and diagnosis of mesothelioma

BACKGROUND Mesothelioma is a highly aggressive tumour for which there are no reliable serum tumour markers. Identification of such a marker would be useful in diagnosis of mesothelioma and for monitoring responses to treatment and screening at-risk individuals. METHODS We assayed serum concentrations of soluble mesothelin-related proteins (SMR) using a double determinant (sandwich) ELISA in a blinded study of serum samples from 44 patients with histologically proven mesothelioma; 68 matched healthy controls, 40 of whom had been exposed to asbestos; and 160 patients with other inflammatory or malignant lung and pleural diseases. FINDINGS 37 (84%) of 44 patients with mesothelioma had raised concentrations of SMR at a serum dilution of 1/80, compared with three (2%) of 160 patients with other cancers or other inflammatory lung or pleural diseases, and with none of 28 controls who had not been exposed to asbestos. SMR concentrations correlated with tumour size and increased during tumour progression. Seven of the 40 asbestos-exposed individuals had increased serum concentrations of SMR; three of those seven developed mesothelioma and one developed lung carcinoma within 1-5 years. None of the 33 asbestos-exposed participants whose serum samples had normal concentrations of SMR and who were followed up over 8 years developed mesothelioma. INTERPRETATION Determination of SMR in serum could be a useful marker for diagnosis of mesothelioma and to monitor disease progression. It might also prove helpful for screening asbestos-exposed individuals for early evidence of mesothelioma.

Cellular Immunity Against Tumor Antigens

Publisher Summary This chapter summarizes the evidence that tumors possess tumor-specific transplantation antigens (TSTA). Virtually all animal neoplasms contain TSTA. Immune reactions against the specific antigens of syngeneic tumors are similar to allograft reactions by which transplanted normal and tumor cells are rejected if they contain isoantigens that are foreign to the recipients. They are to a large extent mediated by immunologically competent cells—that is, lymphocytes and macrophages. The chapter describes several techniques by which cellular immunity to transplantation antigens can be demonstrated, along with a review of different systems in which such techniques were used to detect lymphocyte-mediated immune reactions to TSTA. TSTA are macromolecules present in tumor cells and absent in the normal cells of the same individual and against which immune reactions can be demonstrated with transplantation techniques. The transplantation methods used to demonstrate TSTA can involve the immunization of recipient animals with tumor cells that have been rendered incapable of multiplication (X-irradiation) or that are inoculated in subthreshold doses. Immunization can be also achieved by the inoculation of living tumor cells and excision of the subsequent tumor nodule. The possible role of cellular immunity to TSTA is also discussed in the chapter. The demonstration of cellular immunity to TSTA implies that autochthonous neoplasms appear in the presence of immune lymph node cells, which can destroy their cells at least in vitro . The chapter reviews the phenomenon of allogeneic inhibition. This phenomenon has been postulated to operate in parallel to the immunological mechanisms as part of the organisms defense against antigenic neoplastic cells.

Selection of Potential Markers for Epithelial Ovarian Cancer with Gene Expression Arrays and Recursive Descent Partition Analysis

Purpose: Advanced-stage epithelial ovarian cancer has a poor prognosis with long-term survival in less than 30% of patients. When the disease is detected in stage I, more than 90% of patients can be cured by conventional therapy. Screening for early-stage disease with individual serum tumor markers, such as CA125, is limited by the fact that no single marker is up-regulated and shed in adequate amounts by all ovarian cancers. Consequently, use of multiple markers in combination might detect a larger fraction of early-stage ovarian cancers. Experimental Design: To identify potential candidates for novel markers, we have used Affymetrix human genome arrays (U95 series) to analyze differences in gene expression of 41,441 known genes and expressed sequence tags between five pools of normal ovarian surface epithelial cells (OSE) and 42 epithelial ovarian cancers of different stages, grades, and histotypes. Recursive descent partition analysis (RDPA) was performed with 102 probe sets representing 86 genes that were up-regulated at least 3-fold in epithelial ovarian cancers when compared with normal OSE. In addition, a panel of 11 genes known to encode potential tumor markers [mucin 1, transmembrane (MUC1), mucin 16 (CA125), mesothelin, WAP four-disulfide core domain 2 (HE4), kallikrein 6, kallikrein 10, matrix metalloproteinase 2, prostasin, osteopontin, tetranectin, and inhibin] were similarly analyzed. Results: The 3-fold up-regulated genes were examined and four genes [Notch homologue 3 (NOTCH3), E2F transcription factor 3 (E2F3), GTPase activating protein (RACGAP1), and hematological and neurological expressed 1 (HN1)] distinguished all tumor samples from normal OSE. The 3-fold up-regulated genes were analyzed using RDPA, and the combination of elevated claudin 3 (CLDN3) and elevated vascular endothelial growth factor (VEGF) distinguished the cancers from normal OSE. The 11 known markers were analyzed using RDPA, and a combination of HE4, CA125, and MUC1 expression could distinguish tumor from normal specimens. Expression at the mRNA level in the candidate markers was examined via semiquantitative reverse transcription-PCR and was found to correlate well with the array data. Immunohistochemistry was performed to identify expression of the genes at the protein level in 158 ovarian cancers of different histotypes. A combination of CLDN3, CA125, and MUC1 stained 157 (99.4%) of 158 cancers, and all of the tumors were detected with a combination of CLDN3, CA125, MUC1, and VEGF. Conclusions: Our data are consistent with the possibility that a limited number of markers in combination might identify >99% of epithelial ovarian cancers despite the heterogeneity of the disease.

Serum mediated inhibition of cellular immunity to methylcholanthrene-induced murine sarcomas

Abstract The colony inhibition test was used to demonstrate cellular immunity to primary methylcholanthrene (MCA)-induced mouse and rat tumors. Serum from the tumor-bearing animals, obtained at the time of tumor removal and explantation into culture, abrogated the inhibitory effect of autochthonous lymph node cells (LNC). Serum taken before palpable tumors could be detected did not abrogate the inhibitory LNC effect. Lymph node cells from mice transplanted with MCA-induced tumors inhibited colony formation of the respective tumors, and serum from the same mice abrogated the LNC effect, even when harvested before the appearance of palpable tumors. Cellular immunity but no blocking effect with serum was seen in mice transplanted with MCA tumor cells that did not develop tumors. Splenectomized animals had less blocking activity in their serum than did their shamoperated controls. The blocking activity of serum from mice transplanted with MCA sarcomas decreased within 4 days following tumor removal.

Gene therapy for cancer using single-chain Fv fragments specific for 4-1BB

Monoclonal antibodies against the T-cell activation molecule 4-1BB have been effective in the treatment of established mouse tumors. To create a vaccine that stimulates the immune system similarly to the efficacious monoclonal anti-4-1BB antibody, 1D8, we constructed a vector encoding cell-bound single-chain Fv fragments from 1D8. We transfected the vector into cells from the K1735 melanoma, selected because of its low immunogenicity and very low expression of major histocompatibility complex class I. The transfected cells induced a strong type 1 T-helper cell response, for which CD4+ but not CD8+ T lymphocytes were necessary and that involved natural killer cells. Vaccinated mice rejected established wild-type K1735 tumors growing as subcutaneous nodules or in the lung. An analogous approach may be effective against micrometastases in human patients, including tumors whose expression of major histocompatibility complex class I is very low.

A colony inhibition (CI) technique for demonstration of tumor cell destruction by lymphoid cells in vitro

A colony inhibition technique is described which was used to demonstrate that immune lymphocytes have a destructive effect on cultivated tumor target cells, if the target cells contain H‐2 isoantigens or tumor‐specific antigens foreign to the lymphocytes. Untreated allogeneic lymphocytes and lymphoma cells, added to the target cells together with phytohemagglutinin, were also effective in reducing the number of colonies formed.

Cutting Edge: CD83 Regulates the Development of Cellular Immunity

We recently found that human CD83, a marker of mature dendritic cells, is an adhesion receptor that binds to resting monocytes and a subset of activated CD8+ T cells. We injected CD83-Ig into mice transplanted with the immunogenic P815 mastocytoma and showed that it significantly enhanced the rate of tumor growth and inhibited the development of cytotoxic T cells. In contrast, mice immunized with CD83-transfected K1735 cells, a poorly immunogenic melanoma, could prevent the outgrowth of wild-type K1735 cells. Studies performed in vitro with human PBL showed that coimmobilized CD83-Ig and anti-CD3 enhanced T cell proliferation and increased the proportion of CD8+ T cells. CD83-transfected B-lymphoblastoid T51 cells stimulated T cell proliferation more effectively than untransfected T51 cells in MLR cultures and increased the generation of cytolytic T cells. We conclude that CD83 is a functionally important receptor that can regulate the development of cellular immunity by interacting with its ligand(s).

Mesothelin Variant 1 Is Released from Tumor Cells as a Diagnostic Marker

The mesothelin family comprises (at least) three variants and includes the precursor for megakaryocyte potentiating factor (MPF). Assaying soluble mesothelin-related protein (SMRP) molecules in serum and other body fluids from patients with certain cancers can provide diagnostically useful information. We have constructed fusion proteins of mesothelin variants 1, 2, and 3, made monoclonal antibodies, and investigated the binding specificity of these and three previously generated monoclonal antibodies to each of the three mesothelin variants. According to flow cytometry, the molecule that is most frequently expressed at the surface of cells from ovarian carcinomas and certain other tumors is mesothelin variant 1. Similarly, SMRP released into ascites from a patient with ovarian carcinoma was shown to have a molecular weight of ∼40 kDa and, according to sequencing, to be variant 1. A published sandwich ELISA was shown to detect variants 1 and 3 and to be much more sensitive than a newly constructed ELISA, which detects only variant 3, the former being positive in 28 of 41 (68%) sera from patients with ovarian cancer as compared with 6 of 41 sera (15%). A standard curve was constructed to measure SMRP with a limit of detection of 200 pg/mL to facilitate future quantitative studies. (Cancer Epidemiol Biomarkers Prev 2006;15(5):1014–20) (Cancer Epidemiol Biomarkers Prev 2006;15(5):1014-1019)