Complement 3 (C3) is one of the most important proteins in the complement system, which is a group of proteins that play a crucial role in the immune response and in the clearance of immune complexes. The complement system is essential for innate immunity and aids in the adaptive immune response. It helps in lysing of microbial cells, promotes phagocytosis, and contributes to inflammation. C3 is central to the complement activation pathways - the classical, alternative, and lectin pathways.
C3 is pivotal in the complement system. When the complement system is activated by one of the pathways, C3 is cleaved into C3a and C3b. C3b aids in the opsonization of pathogens, which enhances phagocytosis by immune cells. C3a is an anaphylatoxin which is involved in inflammation.
The measurement of C3 levels in the blood is mainly used to help diagnose conditions that cause inflammation and to monitor disease activity and the effectiveness of treatment. It can be particularly helpful in the diagnosis and monitoring of certain autoimmune diseases such as lupus (SLE). Low levels of C3 can be indicative of a consumption of complement due to the ongoing immune complex formation and clearance, as is often seen in active lupus.
Blood is usually drawn from a vein in the arm. The skin is cleaned with an antiseptic, and a tourniquet is applied above the injection site to slow down blood flow, which allows blood to be drawn more easily. The patient might feel a moderate sting or pinch. The blood sample is then sent to the laboratory for analysis.
Normal ranges for C3 can vary between laboratories but are usually around 90-180 mg/dL.
No, it's often done as part of a group of tests measuring complement activity.
There are no special preparations needed for the C3 blood test.
Treatment depends on the underlying condition; this might include steroids for autoimmune conditions, antibiotics for infections, and various other immunosuppressants.
There is no substantial evidence to suggest that any particular supplement or food has a direct effect on C3 levels.
Symptoms can include fatigue, joint pain, and in severe cases, kidney dysfunction.
C3 is a central component of the complement system, essential for both innate and adaptive immunity. Its levels are used in the diagnosis and monitoring of diseases with immune complex formation like lupus. Understanding C3 and its role in immunity can be crucial for both patients and healthcare providers in the management of autoimmune and inflammatory conditions.