In medicine, acute phase reactants refer to a group of proteins that are produced by the liver in response to inflammation or tissue injury. These proteins are part of the body’s acute phase response, which is a complex biological response that occurs in response to a wide range of conditions, such as infection, trauma, surgery, cancer, and autoimmune disorders.
Examples of acute phase reactants include C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, and haptoglobin. These proteins are elevated in the blood within hours of the onset of inflammation or injury, and their levels typically peak within 48-72 hours.
The main function of acute phase reactants is to help the body fight infection and promote tissue repair. For example, CRP binds to bacterial cell walls and enhances the activity of immune cells, while fibrinogen helps to form blood clots to stop bleeding at the site of injury.
Measurement of acute phase reactants is commonly used in clinical practice as a diagnostic and prognostic tool for a variety of conditions. Elevated levels of these proteins are typically associated with acute and chronic infections, inflammatory diseases, and certain cancers. Monitoring changes in the levels of acute phase reactants over time can also help to track disease progression and response to treatment.