Effect of IL-15 on APAP Hepatitis Figure 5. Inductions of hepatic inflammatory genes are greater in Il152/2 than WT mice with APAP challenge. Relative mRNA levels of (A) pro-inflammatory cytokines IL-1b, TNFa and IL-6; (B) vascular adhesion molecules ICAM-1 and VCAM-1; and (C) chemokines MIP-1a, KC/GRO and MIP-2a at indicated times after injection with APAP. *P,0.05; **P,0.01; ***P,0.001; #P,0.05 compared with WT at 0 hr. Data are mean 6 SEM from 6,8 mice per group. doi:10.1371/journal.pone.0044880.g005 These results suggested that reconstitution or neutralization of IL- 15 would not influence the susceptibility of mice to APAP, implicating a probable intracellular, but not extracellular, role of IL-15 within KC during AILI, or otherwise, a secondary phenomenon of elevated serum IL-15 in APAP hepatitis. In view of the up-regulated IL-15 expression in KC fraction of WT mice after APAP challenge (Figure 2C), we further examined the role of innate immunity in IL-15 protection against AILI. KCs but not neutrophils might play a major role in the heightened sensitivity to APAP in Il152/2 mice Innate immune cells play an important role in APAP hepatitis [39]. To assay whether innate immune cells, such as neutrophils and KCs, are involved in exacerbated AILI of Il152/2 mice, we used vinblastine and GdCl3 for further experiments. Vinblastine, a mitosis inhibitor, was used to induce neutropenia in a mouse ischemia/reperfusion model [40]. Neutrophil depletion was confirmed by flow cytometry in mice (data not shown). Although increased neutrophil infiltration of liver was observed after APAP treatment in Il152/2 mice, pre-treatment of vinblastine could not alter the vulnerability of Il152/2 mice to AILI, based on the serum PLOS ONE | www.plosone.org 7 September 2012 | Volume 7 | Issue 9 | e44880