A novel monoclonal antibody for detection of galectin-9 in tissue sections : application to human tissues infected by oncogenic viruses.

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Barjon, Clément | Niki, Toshiro | Vérillaud, Benjamin | Opolon, Paule | Bedossa, Pierre | Hirashima, Mitsuomi | Blanchin, Stéphanie | Wassef, Michel | Rosen, Hugo | Jimenez, Anne-Sophie | Wei, Ming | Busson, Pierre

Edité par CCSD ; BioMed Central -

International audience. ABSTRACT: BACKGROUND: Galectin-9 is a mammalian lectin which possesses immunosuppressive properties. Excessive production of galectin-9 has been reported in two types of human virus-associated diseases : chronic hepatitis C and nasopharyngeal carcinoma associated to the Epstein-Barr virus. The objective of this study was to produce new monoclonal antibodies targeting galectin-9 in order to improve its detection in clinical samples especially on tissue sections analysed by immunohistochemistry. METHODS: Hybridomas were produced through immunization of mice with the recombinant c-terminal part of galectin-9 (residues 149 to 311 of the S-isoform) and semi-solid fusion of spleen cells with Sp2/0 cells. Monoclonal antibodies were characterized using ELISA, epitope mapping, western blot and immunohistochemistry. RESULTS: We selected seven hybridomas producing antibodies reacting with our recombinant c-terminal galectin-9 in ELISA. Five of them reacted with the epitope "TPAIPPMMYPHPA" (residues 166 to 178 of the S-isoform) and stained all three isoforms of galectin-9 analysed by western blot. One of them, 1G3, demonstrated very good sensitivity and specificity when used for immunohistochemistry. Using 1G3, we could confirm the intense and constant expression of galectin-9 by Epstein-Barr virus positive malignant cells from nasopharyngeal carcinomas. In most samples, specific staining was detected in both cytoplasm and nuclei. Galectin-9 was also detected in liver biopsies from patients infected by the human hepatitis C or B viruses with expression not only in inflammatory leucocytes and Kupffer cells, but also in hepatocytes. In contrast, galectin-9 was virtually absent in non-infected liver specimens. CONCLUSION: The 1G3 monoclonal antibody will be a powerful tool to assess galectin-9 expression and distribution especially in diseases related to oncogenic viruses.

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