Complement C4a

Complement C4a or complement component 4a is a glycoprotein and peptide that is expressed, primarily in the liver and in macrophages, in response to acute inflammation or tissue injury. Complement C4a is part of the Complement C4 family.

ME/CFS
Increased C4a levels have been found one to six hours after exercise challenge tests in ME/CFS patients but not in healthy controls.

Nijs et al. (2010) found a strong relation between the change in complement C4a level and an increase in post-exertional pain and fatigue in ME/CFS patients. Previously, complement C4a, in combination with other proteins, was being considered as a potential diagnostic biomarker of post-exertional malaise in ME/CFS.

Notable studies

 * 2003, Complement activation in a model of chronic fatigue syndrome - (Abstract)
 * 2009, Transcriptional Control of Complement Activation in an Exercise Model of Chronic Fatigue Syndrome - (Full text)
 * 2010, Unravelling the nature of postexertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome: the role of elastase, complement C4a and interleukin-1β - (Abstract)

Learn more

 * The Role of Anaphylatoxins in Health and Disease