Abstract 1241: Characterization of a newly developed anti-TIGIT monoclonal antibody by double staining of T cells and NK cells by IHC and FACS

Abstract

Abstract T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory domain (TIGIT) is a newly identified surface protein expressed in regulatory, memory, naturalkiller (NK), and activated T cells. Several studies indicate that mouse TIGIT is a vital immunomodulator that can control the activities of both NK and T cells and plays an important role in transplantation tolerance and tumor immune surveillance. In this study, we generated a mouse monoclonal antibody, clone: BC41, by immunizing a recombinant human TIGIT, corresponding to an extra cellular domain. The protein was injected into BALB/c mice for three times and then the splenocytes were electro fused with mouse myeloma cells. The TIGIT-specific hybridoma cells were screened and a TIGIT-specific clone, named as BC41, was selected. The BC41 antibody was characterized by Western blot and immunohistochemistry. In immunoblots, TIGIT was able to detect a 26 kda protein corresponding to human TIGIT on over-expressed cells and native protein in human spleen lysates. Moreover, the BC41 was able to bind mouse TIGIT. FACS result showed that the BC41 antibody bond specifically to CD3/CD28+ T cells. We further analyzed the antibody binding profile by Immunohistochemistry on human T cells and NK cells by double staining. BC41 was able to bond portion of CD8 T cells (EOMES+), Treg cells (FOXP3+), PD1+ T cells and NK (CD57+) cells. Our results demonstrated that the antibody is TIGIT-specific and can be applied for detecting and analyzing tumor-infiltrating cells profile in transplantation and tumor immunotherapy. Citation Format: Weimin Qi, Joseph Chu, Lily Luo, Tatiana Scoggin, Kim Dickinson. Characterization of a newly developed anti-TIGIT monoclonal antibody by double staining of T cells and NK cells by IHC and FACS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1241.