ABSTRACT
The ultimate function of the acute phase proteins and the purpose of the acute phase response is the maintenance of extracellular homeostasis. The composition of the extracellular environment shows tissue-specific variations, in particular, different patterns of protein concentrations. The organization of the extracellular environment of the body into different compartments, which contain plasma proteins in different concentrations, leads to the question of the origin of these proteins. The name “plasma protein” has been coined and retained because this type of protein is most easily obtained from the bloodstream, even though its major proportion and function might be located outside the bloodstream. The study of extrahepatic protein synthesis by measuring incorporation of radioactive amino acids into proteins in vivo is hampered by the fact that all tissues contain plasma proteins, derived from the liver, in their vascular and interstitial compartments.
