Advanced Diagnostic Laboratories

C3 Function

Test Code

C3F

Description

The complement system is part of our innate immune response. It is vital to our defense against invasive microorganisms. Complement activation can occur through the classical, lectin and alternative pathway, which then converge to a common terminal pathway. Complement deficiency can lead to life-threatening infections as well as long-term autoimmune conditions such as systemic lupus erythematosus (SLE) and hereditary angioedema (HAE).

The C3 hemolytic assay is a sensitive method for detection of complement protein C3 activity or lack thereof. C3 is the central protein of all three pathways and the most abundant protein of the complement system. Severe or recurrent infections that produce strong activation of either complement pathway can lead to low C3 protein levels and reduced C3 activity. Low or absent C3 activity is also observed with genetic deficiencies of C3 that lead to a lack of or insufficient production of C3 protein. Low C3 activity can be associated with low CH50 and AH50 activity.

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