Acute-phase proteins

Definition

Acute-phase proteins are a group of proteins whose plasma concentrations increase or decrease in response to inflammation. They play a crucial role in the innate immune response by enhancing the body's ability to fight infections and promote tissue repair. These proteins are primarily produced by the liver and can act as markers for inflammation, helping to indicate the presence and severity of an immune response.

5 Must Know Facts For Your Next Test

1. Acute-phase proteins are primarily synthesized by hepatocytes in the liver during an inflammatory response.
2. The levels of acute-phase proteins can be measured through blood tests, providing insight into the presence and intensity of inflammation in the body.
3. Besides CRP, other notable acute-phase proteins include serum amyloid A, haptoglobin, and alpha-1 antitrypsin.
4. The increase in acute-phase proteins can lead to various physiological changes, such as altered iron metabolism, which helps limit bacterial growth during infections.
5. Acute-phase protein levels can vary based on several factors, including age, gender, and underlying health conditions.

Review Questions

• How do acute-phase proteins contribute to the body's defense mechanisms during an inflammatory response?
  • Acute-phase proteins enhance the innate immune response by promoting opsonization of pathogens, recruiting immune cells to sites of infection, and regulating inflammation. For example, C-reactive protein binds to dead or dying cells and pathogens, marking them for destruction by phagocytes. This process helps to eliminate infections more efficiently while also contributing to tissue repair mechanisms.
• Discuss the role of interleukin-6 in the regulation of acute-phase proteins and its significance in inflammation.
  • Interleukin-6 is a crucial cytokine that mediates inflammation and stimulates the liver to produce acute-phase proteins. During an inflammatory response, IL-6 levels rise, triggering the synthesis of various acute-phase proteins, including CRP and fibrinogen. This connection highlights IL-6's importance not only as a signaling molecule in inflammation but also as a potential therapeutic target for controlling excessive inflammatory responses.
• Evaluate the clinical significance of measuring acute-phase proteins in diagnosing and monitoring diseases.
  • Measuring acute-phase proteins such as C-reactive protein is clinically significant because it provides valuable information about ongoing inflammation within the body. Elevated levels can indicate various conditions ranging from infections and autoimmune diseases to chronic inflammatory disorders. By tracking changes in acute-phase protein levels over time, healthcare providers can monitor disease progression or response to treatment, making these biomarkers essential tools in clinical practice.

Related terms

C-reactive protein (CRP): A specific type of acute-phase protein that increases significantly in response to inflammation and is often used as a clinical marker to assess inflammatory conditions.

Interleukin-6 (IL-6): A cytokine that plays a key role in the inflammatory response and stimulates the production of acute-phase proteins in the liver.

Fibrinogen: An acute-phase protein involved in blood clotting, which also increases during inflammatory responses, contributing to tissue repair and healing.