Acute phase reactants

It is an increase in the concentration of serum proteins (APR) accompanies inflammation and tissue injury. Focus on the acute phase phenomenon, termed the acute phase response, first occurred with the discovery of C-reactive protein (CRP) in the serum of patients during the acute phase of pneumococcal pneumonia. During the acute phase response, usual levels of various proteins maintained by homeostatic mechanisms can change substantially. These changes are thought to contribute to host defense and other adaptive capabilities.

1. Acute Phase Reactants (APR)[1] by Dr. Tasneem Bashir
It is an increase in the concentration of serum proteins (APR) accompanies inflammation and tissue
injury. Focus on the acute phase phenomenon, termed the acute phase response, first occurred with
the discovery of C-reactive protein (CRP) in the serum of patients during the acute phase of
pneumococcal pneumonia. During the acute phase response, usual levels of various proteins
maintained by homeostatic mechanisms can change substantially. These changes are thought to
contribute to host defense and other adaptive capabilities.
The acute phase response: it accompanies both acute and chronic inflammatory states associated
with a wide variety of disorders, including infection, trauma, infarction, inflammatory arthritides and
other systemic autoimmune and inflammatory diseases, and various neoplasms. Acute phase
proteins are defined as those proteins whose serum concentrations increase or decrease by at least
25% during inflammatory states. Such proteins are termed either positive or negative acute phase
reactants (APR), respectively. The erythrocyte sedimentation rate (ESR), a nonprotein or indirect
APR, reflects plasma viscosity and the presence of acute phase proteins, especially fibrinogen, as
well as other influences, some of which are as yet unidentified.
Positive phase reactant:
1- ESR
2- CRP
3- Ferritin
4- Haptoglobin
5- Fibrinogen
6- C3 & C4
7- Serum Amyloid
8- Alpha-1 antitrypsin

Negative phase reactants:
1- Albumin
2- Transferrin
3- Transthyretin
4- Retinol binding protein



References:
[1] (UpToDate) website