In addition to recognizing endotoxin, TLR4 also recognizes endogenous ligands (‘damage-associated structures’), which are released into the circulation in the peri-transplantation period. TLR2 to a lesser extent also recognizes these endogenous ligands. Rapamycin ic50 multiple studies involving solid organ transplants demonstrate

a clear association between TLR4 and allograft rejection. In the present study we assessed whether an association exists between TLR4 and TLR2-dependent responses and acute liver allograft rejection. Methods:  The sample included 26 liver transplant recipients. Blood was taken pre-transplant and at multiple points over the first 14 days post-transplant. Monocytes were stimulated with TLR4 and TLR2 ligands, lipopolysaccharide and Pam-3-Cys, respectively. Monocyte TLR expression was determined using flow cytometry; enzyme-linked immunosorbent assays measured tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) production. Results:  Nine (34.6%) patients experienced rejection. No differences existed in age, sex, disease or immunosuppression between rejectors and non-rejectors. Baseline TLR4 expression was significantly higher in rejectors (1.36 vs 1.02, P = 0.01). There was no difference in TLR2 expression. In rejectors, baseline TLR4- and TLR2-dependent production of TNF-α

and IL-6 was also significantly increased. Post-transplant, the two groups differed with regard to TLR4-dependent TNF-α production, with rejectors demonstrating progressive downregulation

over the first week. Conclusions:  Prior to liver transplantation, patients who subsequently experience rejection demonstrate robust TLR4-dependent immune responses, which are not seen in those who do not reject. This supports the theory that damage-associated structures signaling through TLR4 may be responsible for the early activation of alloimmune T-cells, favoring allograft rejection. “
“See Article on Page 434 The World Health Organization (WHO) defines chronic hepatitis B virus (HBV) infection as persistent hepatitis B surface antigen (HBsAg) positivity in blood for at least 6 months and acute HBV infection as the Guanylate cyclase 2C transient presence of hepatitis B surface antigenemia.1 The HBsAg can be found in the blood of infected individuals in a number of different particulate forms: complete virions of ∼42 nm in diameter2 and subviral particles that are either spherical and 20-22 nm in diameter or filamentous forms of various lengths with a width of ∼20 nm.2 These noninfectious subviral particles are typically produced in excess over the infectious virions by several orders of magnitude and can accumulate in blood to concentrations ranging from 50-300 μg/mL.3 The HBsAg found in serum is in fact a mosaic of viral envelope proteins and can contain all three forms of the surface proteins of the mature HBV virion, the large (L), medium (M), and small (S) proteins.