Tumor Antigen Expression in Primary Ovarian Cancer Cells

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T.49. Tumor Antigen Expression in Primary Ovarian Cancer Cells Hana Hromadkova, Anna Fialova, Dagmar Viktorova, Tomas Brtnicky, Lukas Rob, Jirina Bartunkova, Radek Spisek. Charles University, University Hospital Motol, Prague, Czech Republic Ovarian cancer is diagnosed in more than 190,000 new patients every year and is known to have the highest mortality rate among gynaecologic cancers. Due to the lack of satisfactory biomarkers and the fact that the disease develops and spreads very rapidly, almost 70% of patients with diagnosed ovarian cancer already suffer from advanced disseminated disease. Since cells that underwent malignant transformation can express antigens recognized by the immune system as foreign, cancer development as well as treatment of the disease is markedly affected by the patient's immune system. To extend the knowledge of tumor-associated antigens (TAA) expressed by primary ovarian cancer cells, we analysed expression of Her-2/ neu, CA-125, FBP, NY-ESO-1, MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A10 and MAGE-A12 TAA genes using quantitative RT–PCR. Three most frequent TAA genes, Her-2/neu, CA-125 and FBP, were overexpressed in 94%–100% of samples, whereas the expression frequency of the other tested TAA varied between 29% and 59%. Our data show that primary ovarian cancer cells express a wide spectrum of TAA genes which may represent potential targets of immunotherapy and/or might be revealed as possible prognostic factors in ovarian cancer patients. The project was supported by project MSM 0021620812 from the Czech Ministry of Education and grant GACR 310/08/0838. doi:10.1016/j.clim.2010.03.163

T.50. The TCR β-chain CDR2 Loop Governs Vβ-specificity by Bacterial Superantigens Nur-Ur Rahman 1, Fraser Pollard 1, Christine Herfst 1, Michael Peirce 1, Aaron Wyatt 1, Jean-Nicholas Brouillard 1, Katherine Kasper 1, Joaquîn Madrenas 2, Eric Sundberg 3, John McCormick 1. 1The University of Western Ontario, London, ON, Canada; 2Robarts Research Institute, London, ON, Canada; 3Boston Biomedical Research Institute, Boston, MA Superantigens (SAgs) represent microbial toxins defined by their ability to induce massive T cell activation in a TCR Vβspecific manner. They have been implicated in many immunemediated diseases, such as toxic shock syndrome and autoimmune diseases. To ameliorate SAg-mediated diseases, the molecular basis of Vβ specificity and activation by SAgs needs to be understood. It is known that evolutionally diverse bacterial SAgs engage distinct regions of Vβ and all commonly target the CDR2β loop. Previous work from our laboratory had identified a hotspot region on the surface of a SAg that exclusively interacted with the CDR2β loop of the human Vβ2 TCR. Herein, we define the functional epitope of two diverse SAgs on the surface of their common binding partner, the human Vβ2 TCR. Our work demonstrates that a hotspot binding region for both SAgs exists on the CDR2β loop and the structural conformation of the CDR2β loop is critical for the activation of T cells. In

Abstracts addition, we have employed SAg domain swapping to change Vβ specificity of two group V SAgs that engage the CDR2β and FR3/ 4β regions of the TCR Vβ chain using two distinct SAg domains. Through domain-swapping between group V staphylococcal and streptococcal SAgs with known Vβ-specificity, we show that Nterminal α-helix domain of group V SAgs, which makes exclusive contacts with CDR2β, dictates Vβ-specificity. This information may be important for the rationale design of SAg antagonists. doi:10.1016/j.clim.2010.03.164

T.51. Polyfunctional CD8+ T Cell Responses Did Not Predict Efficient Suppression of HIV-1 Replication Olusimidele Akinsiku, Paul Goepfert. University of Alabama at Birmingham, Birmingham, AL CD8+ cytotoxic T lymphocytes (CTL) play an important role during HIV-1 infection, yet it is unclear which components of the response are critical for protection. The detection of IL-2producing, HIV-1-specific CD8+ T cells that maintain proliferative capacity is a strong correlate of delayed disease progression. We predicted that IL-2 production identifies a population of effector CD8+ T cells with enhanced ability to (1) produce anti-viral soluble factors and (2) restrict HIV-1 replication as detected using an in vitro suppression assay (iVSA). HIV-1specific CTL responses were analyzed in subjects chronically infected with HIV-1 (viral load less than 2000 RNA copies/mL) and off antiretroviral therapy (ART). Peptides yielding positive responses (by ELISpot) were used to expand CTL lines that were analyzed for virus suppression capacity and the production of CD107a, IL-2, interferon-gamma (IFN-γ), tumor necrosis factoralpha (TNF-α), and perforin. We expanded polyfunctional, epitope-specific CTL lines, many of which produced IL-2. Analysis of effector function using the iVSA revealed differential suppression of HIV-1 replication various CTL lines. IL-2 production alone was not predictive of suppressive capacity. Further analysis of effector function—production of CD107a, IFN-γ, TNFα, and perforin—did not reveal an association with the ability of a CTL line to suppress virus replication. The suppressive capacity of an HIV-1-specific CTL line cannot be easily predicted using methods commonly applied to study CTL function. These results have important implications for the analysis of CTL responses induced by HIV-1 vaccine strategies. doi:10.1016/j.clim.2010.03.165

T.52. Promoter Variant of PIK3C3 is Associated with Autoimmunity Against Ro and Sm Epitopes in African-american Lupus Patients Silvia Kariuki 1, Beverly Franek 1, Rachel Mikolaitis 2, Meenakshi Jolly 2, Tammy Utset 1, Andrew Skol 2, Timothy Niewold 1. 1University of Chicago, Chicago, IL; 2Rush University, Chicago, IL Background: The PIK3C3 locus was implicated in case–case genome-wide association study of systemic lupus