Abstract 4769: Relevance of the TRIF pathway for in vivo gp96-mediated CD8+ T cell cross presentation

Abstract

Abstract Heat shock protein gp96 is an intracellular chaperone for proteins and peptides generated during protein synthesis and degradation. Different candidate receptors including CD91, TLR2 and TLR4 have been shown as important binders in the gp96 mediated cross-priming process. Both TLR2 and TLR4 use the common MyD88 signaling pathway suggesting it is an important mediator of gp96-mediated cross-priming. Our group has produced a secreted form of hsp-gp96, a fusion protein gp96-Ig. Ggp96-Ig-transfected tumor cells secrete gp96-Ig in vivo and cross prime CD8 CTL that are specific for genuine tumors antigens (Ag) and for the surrogate Ag OVA. In this work, we studied the role of both MyD88 and TRIF signaling pathways in gp96-mediated cross presentation. Briefly, one million of ovalbumin specific T cell receptor (TCR) transgenic CD8+ cells (OT-I)-gfp, were transferred intravenously into MyD88 deficient (MyD88−/−) mice, TRIF deficient (TRIF Lps2/Lps2) mice and C57/BL6 wild type (B6-WT) mice as control. Two days later the mice were immunized intraperitoneally with two million of 3T3-gp96-mIgG1-OVA cells or 3T3-OVA cells respectively. Five days later, we obtained peritoneal cells (PECs) and splenocytes in order to analyze OT-I-gfp expansion, IFNγ production, CD107a degranulation and cytokine (IL-6, TNFα, IL-10) production by ELISA. Gp96 induced CD8 CTL (OT-I) expansion is significantly increased in MyD88−/− mice compared to WT mice and significantly decreased in TRIF deficient mice. However, the frequency of IFNγ expression in CTL is diminished in MyD88−/− while is normal in TRIF deficient mice. IL-6 and TNFα production by antigen presenting cells isolated from the peritoneal cavity, was reduced in MyD88−/− mice compared with WT and TRIF deficient mice. The data indicate that both, MyD88 and TRIF mediated signals are required for full CD8 CTL expansion and cytotoxic differentiation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4769.