Acute-phase proteins (APPs) are a class of proteins whose concentrations in blood plasma either increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation. This response is called the acute-phase reaction (also called acute-phase response). The acute-phase reaction characteristically involves fever, acceleration of peripheral leukocytes, circulating neutrophils and their precursors. The terms acute-phase protein and acute-phase reactant (APR) are often used synonymously, although some APRs are (strictly speaking) polypeptides rather than proteins. In response to injury, local inflammatory cells (neutrophil granulocytes and macrophages) secrete a number of cytokines into the bloodstream, most notable of which are the interleukins IL1, and IL6, and TNF-α. The liver responds by producing many acute-phase reactants. At the same time, the production of a number of other proteins is reduced; these proteins are, therefore, referred to as "negative" acute-phase reactants. Increased acute-phase proteins from the liver may also contribute to the promotion of sepsis. Regulation of synthesis
TNF-α, IL-1β and IFN-γ are important for the expression of inflammatory mediators such as prostaglandins and leukotrienes, and they also cause the production of platelet-activating factor and IL-6. After stimulation with proinflammatory cytokines, Kupffer cells produce IL-6 in the liver and present it to the hepatocytes. IL-6 is the major mediator for the hepatocytic secretion of APPs. Synthesis of APP can also be regulated indirectly by cortisol. Cortisol can enhance expression of IL-6 receptors in liver cells and induce IL-6-mediated production of APPs. Positive
Positive acute-phase proteins serve (as part of the innate immune system) different physiological functions within the immune system.
Sterile or sterility may refer to:

Asepsis, a state of being free from biological contaminants
Sterile (archaeology), a sediment deposit which contains no evidence of human activity
Sterilization (microbiology), any process that eliminates or kills all forms of life or removes them from an item or a field
Sterility (physiology), an inability of a living organism to effect sexual reproduction
Infertility, a medical condition which prevents a person, an animal or a plant from bearing children, especially through natural means
Sterile Records, a record label which was formed by Nigel Ayers and Caroline K of the post-industrial music group Nocturnal Emissions in London in 1979

See also
Sterilization (disambiguation)