COMPLEMENT C4 (C4)

Overview

C4 is essential for the activation of the classical complement pathway. Low levels of C4 can indicate conditions like systemic lupus erythematosus (SLE), immune complex diseases, or hereditary angioedema. A deficiency in C4 increases the risk of recurrent bacterial infections, particularly from encapsulated organisms like S. pneumoniae, and may lead to autoimmune diseases due to impaired immune response.