New advances in measurement of complement activation: lessons of systemic lupus erythematosus.
Activation of the complement system plays a fundamental role in the pathogenesis of systemic lupus erythematosus (SLE). For the past several decades, quantifying this process has focused primarily on determination of serum C3 and C4, although the utility of these assays for diagnosis and monitoring disease activity is still debated. During this same timespan, knowledge of the complement system has exploded, with identification of more than 30 proteins, an abundance of newly recognized functions, and even a third pathway of activation. These advances suggest that it is appropriate to revisit the complement system as a potential source of biomarkers for SLE. This paper reviews briefly the role of complement in SLE and other inflammatory diseases, discusses conventional methods for complement measurement and their drawbacks, and focuses on recent advancements in harnessing the complement system for monitoring SLE. Specifically, novel assays that measure cell-bound complement activation products are introduced and their utility as biomarkers of SLE disease activity is discussed.
Liu
Chau-Ching
CC
Lupus Center of Excellence, University of Pittsburgh, S705 Biomedical Science Tower, 3500 Terrace Street, Pittsburgh, PA 15261, USA. joa8@pitt.edu
Manzi
Susan
S
Danchenko
Natalya
N
Ahearn
Joseph M
JM
D015415:Biomarkers / Q000097:blood; D003167:Complement Activation; D003176:Complement C3 / Q000276:immunology / Q000378:metabolism; D003181:Complement C4 / Q000276:immunology / Q000378:metabolism; D003165:Complement System Proteins / Q000276:immunology* / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
D015415:Biomarkers; D003176:Complement C3; D003181:Complement C4; D003165:Complement System Proteins