Acute phase protein

In the context of tissue damage (injury, operation, infection), a non-specific immune reaction ( acute phase reaction , SIRS ) occurs. Endothelial cells , fibroblasts and inflammatory cells such. B. Macrophages in the damaged tissue release messenger substances ("mediators"), e.g. B. interleukin-1 , interleukin-6 , TNF-α , TGF-β , gamma interferon , EGF , LIF and the like. a. that reach the liver via the bloodstream . There, in the presence of cortisol , they stimulate the liver to increase the synthesis of around 30 different acute phase proteins . Their concentration increases one to two thousand times within 6–48 hours after the damaging event.

function

• Localization of inflammation
• Prevention of the spread
• Support of the immune system in cleaning up the focus of inflammation

Acute phase proteins

• Fibrinogen : increases the tendency to clot → local thrombus formation in the inflammation area → pathogens are no longer flushed out into the bloodstream.
• Alpha1-antitrypsin and alpha- antichymotrypsin : counteract the increased release of proteases → reduction of tissue damage.
• C-reactive protein : binds to phosphocholine of the pathogen → opsonization (= "make palatable" for phagocytes ) and activates the complement system through C1q binding
• Serum amyloid A (SAA): induces leukocyte adhesion and the formation of proinflammatory (pro-inflammatory) cytokines
• Orosomucoid (alpha1 acid glycoprotein): promotes fibroblast growth and interacts with collagen
• Haptoglobin : hemoglobin binding and transport to protect against renal excretion
• Ceruloplasmin : inhibits the formation of free oxygen radicals
• Complement -C3: opsonization and chemotaxis
• Complement -MBL: Mannose-binding lectin of the MBL pathway of complement activation
• Plasminogen
• Ferritin : deprivation of iron, which bacteria need for their growth
• Procalcitonin
• Thrombopoietin : promotes megakaryopoiesis and thus the formation of platelets
• Hepcidin : inhibits the iron transporter ferroportin on intestinal mucosal cells and thus reduces the absorption of iron from the intestine into the blood

Anti-acute phase proteins

Anti-acute phase proteins, also known as "negative acute phase proteins", show falling serum concentrations in acute inflammation. They include:

• albumin
• Transferrin
• Antithrombin III
• Transthyretin (prealbumin)
• Retinol binding proteins

swell

Biochemistry & Pathobiochemistry, Löffler Petrides, 7th edition, Springer-Verlag, 2003