low = 57%, odds ratio 3.22, 90% confidence interval 1.16, 8.99, P = 0.045 by Fisher’s test). Further independent CART analysis of biomarkers for BA patients found that IL15, MCP3, MDC, IL17a and MCP1 collectively identified those likely to achieve conjugated/direct bilirubin <1 mg/dL; (AUC of 0.94, sensitivity of 86% and specificity of 93%). Conclusions: Quantification of serum cytokines, chemokines, VEGF and sICAM1 identifies a biomarker profile with discriminatory value for BA, with the potential to sub-classify BA patients and predict response to HPE. Disclosures: John C. Magee - Grant/Research Support: Novartis Jorge A. Bezerra - Grant/Research Support: Molecular Genetics

Laboratory, CHMCThe following people have nothing to disclose: James E. Squires, Kazuhiko Bessho, Lin Fei, Reena ALK targets Mourya, Pranavkumar Shivakumar Background/Aims: Recent studies from our laboratory have assigned independent and synergistic roles for Tnfα receptors, predominantly Tnf-R2 using in vitro assays evaluating cholangiocyte cell death and in vivo in a mouse model of rotavirus (RRV)-induced experimental

atresia. While Tnf-R1 binds to soluble Tnfα, Tnf-R2 preferentially recognizes transmembrane-Tnfα (Tm-Tnfα). Based on the role of Tm-Tnfα in autoimmunity and therapeutic disparity of clinically used anti-TNFα Temsirolimus mw agents, we hypothesized that Tm-Tnfα primarily modulates epithelial injury and duct inflammation in experimental biliary atresia. Methods and Results: Addressing this hypothesis, we quantified Tm-Tnfα expression on NK and CD8 T-cells, the key intrahepatic cell types regulating

atresia phenotype, at days 3, 4 and 7 post saline and RRV injections by flow cytometry. While the anti-Tnfα antibody MP6-XT22 failed to identify Tm-Tnfα, TN3-1 9 antibodies identified increased Tm-Tnfα on CD8 T-cells after RRV at days 3 and 4 (3.5-7.0 fold above controls; P < 0.01). Uniquely, NK cells expressed high and low levels of Tm-Tnfα at the initiation of epithelial injury (day 3) distinguished as Tm-Tnf-bright (44-fold above controls; P < 0.001) and Tm-Tnfα-dim (3-fold above controls; P = 0.001) and as Tm-Tnfα-dim only NK cells at day 7 (2-fold HSP90 above controls; P < 0.01). Since NK cells express Tnfα-receptors, we quantified the expression of the cognate ligand, Tm-Tnfα, on a murine cholangiocyte cell line (mCL). RRVnaϊve mCL constitutively expressed base-line Tm-Tnfα (17.0 ± 3.0%), which increased following RRV infection (36.0 ± 2.0%; P < 0.001). To precisely determine whether TmTnfα expression regulated cytotoxicity, NK cells from livers of day 3 RRV-challenged mice were used in co-culture cytotoxicity experiments with mCL in the presence or absence of TN3-19 Tnfα blocking antibodies. While day 3 RRV NK cells were highly cytotoxic (5–hrs; 15-48% at target: effector ratios of 1: 2.5-1: 25), simultaneous blocking of Tm-Tnfα on NK cells and mCL completely prevented cholangiocyte lysis. Exploring the in vivo role of Tm-Tnfα, neonatal Balb/c mice were challenged with 1.