acute phase proteins

Acute phase proteins are a class of proteins whose plasma concentrations increase (positive acute phase proteins) or decrease (negative acute phase proteins) in response to inflammation. This response is called the acute phase reaction, also known as acute phase response.

Here are the steps to understand acute phase proteins:

1. Definition: Acute phase proteins are proteins that change their plasma concentration in response to inflammation or infection. They are produced mainly in the liver.

2. Types: There are two types of acute phase proteins: positive and negative. Positive acute phase proteins increase their concentration during inflammation (e.g., C-reactive protein, fibrinogen, serum amyloid A). Negative acute phase proteins decrease their concentration during inflammation (e.g., albumin, transferrin).

3. Function: The function of acute phase proteins is to restore homeostasis and promote healing after an injury or infection. They do this by acting as chemoattractants for leukocytes, opsonins for phagocytosis, and initiators of the complement cascade. They also have a role in the coagulation system.

4. Measurement: The level of acute phase proteins can be measured in the blood, and this can be used as a marker of inflammation or infection. For example, a high level of C-reactive protein is often used as a marker of inflammation in conditions like rheumatoid arthritis or lupus.

5. Clinical Significance: Changes in the levels of acute phase proteins can indicate the presence of disease, the severity of the disease, and the effectiveness of treatment. For example, a decrease in the level of albumin, a negative acute phase protein, can indicate malnutrition or liver disease.