Volume 76, Issue 1 p. 1-8


Paul A. Monach

Corresponding Author

Paul A. Monach

VA Boston Healthcare System and Harvard Medical School, Boston, Massachusetts

Address correspondence via email to Paul A. Monach, MD, PhD, at [email protected].

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First published: 08 August 2023

Author disclosures are available at https://onlinelibrary.wiley.com/doi/10.1002/art.42671.


The role of complement in human autoimmune, inflammatory, and infectious diseases is reviewed, focusing on clinical applicability. A typical case is presented in which serum testing for C3 and C4 is performed to help assess a syndrome with a broad differential diagnosis. The review includes a discussion of complement deficiency states, consumption of complement by diseases characterized by immune-complex formation and deposition, usefulness and interpretation of laboratory tests for complement, and development of drugs targeting specific components of the complement pathway for a growing number of indications.