They are rapidly recruited to sites of infection and inflammation. Neutrophils phagocytose invading microbes3 and proceed to kill them by generating superoxide anions and hydrogen peroxide along with other reactive oxygen species (ROS) through activation of nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase,

a process termed respiratory or oxidative burst (OB).4 The OB products are effective in eradicating invading microorganisms, but unfortunately may damage “innocent bystanders,” leading to tissue destruction, inflammation, and organ failure. Neutrophils possess receptors for the Fc region of immunoglobulin G (FcγRIII/CD16 and FcγRII/CD32) and for complement molecules such as iC3b (MAC-1/CD11b-CD18), which bind to the surface of the microbe (opsonization). Complement-opsonized particles are gently internalized within the neutrophil with Fcγ receptor ligation augmenting the process through ITF2357 cell line the extension of pseudopods which surround and engulf the microbe.3 Neutrophils are rapidly recruited to the liver in response to hepatic injury in ALF,5 and once there they become activated

by cytokines (e.g., interleukin [IL]-8 and tumor necrosis factor alpha [TNF-α]), and may contribute to further tissue damage by release of proteolytic enzymes and ROS.6 An exaggerated systemic inflammatory response (SIRS) is frequently present in ALF and increasingly it is being recognized 上海皓元 to play a key role in the pathogenesis and outcome.7 Systemic neutrophil activation with associated immune paresis is well recognized in severe sepsis, selleckchem a condition that shares many phenotypic features with ALF including microvascular dysfunction, hemodynamic instability, coagulopathy, encephalopathy,

and high levels of both proinflammatory and antiinflammatory cytokines.8 In severe sepsis excessive activation of neutrophils has been implicated in the pathogenesis of acute lung and kidney injury.9 Neutrophils might therefore serve as critical effector cells of the progressive parenchymal liver damage and MODS in ALF. There is a high incidence of bacterial and fungal infection early in the course of ALF (10) which may preclude listing for LT. ALF is also associated with an acute and often precipitous increase in plasma ammonia levels.2 A recent study has shown that neutrophils exposed to ammonia have reduced phagocytic activity of opsonized E. coli and high spontaneous production of ROS, suggesting a direct toxic effect of ammonia on neutrophils.11 Neutrophil dysfunction has also been previously reported in ALF with reduced complement expression,12 impaired neutrophil adhesion,13 decreased production of ROS,14 and decreased neutrophil phagocytosis and intracellular killing. We postulate that circulating neutrophil dysfunction is present in ALF and may add value as a prognostic marker of severity and outcome.