Cell-bound complement activation products (CB-CAPs) were first reported in 2004, since which time multiple laboratories have demonstrated their value as biomarkers for diagnosis, monitoring, and stratification of patients with systemic lupus erythematosus. Areas covered: This review summarizes the highlights of these 14 years of CB-CAPs discovery and validation, concluding with a view toward their future potential for precision medicine. Expert commentary: The practice of medicine is both art and science and each physician can be considered both artist and scientist with a variable blend of the two skill sets. There is arguably no disease that presents a greater challenge, nor a greater opportunity, for implementation of precision medicine, as does lupus. The physician who is presented with diagnosis and/or management of a patient suspected of having lupus will need to augment artistic skills with scientific guidance, and that science will be delivered in the form of biomarkers. Ultimately, we will likely have a 'lupus liquid biopsy' that will be 100% sensitive and 100% specific for a diagnosis of lupus. This will undoubtedly be a panel of biomarkers rather than an individual laboratory test. Such a liquid biopsy could transform lupus diagnosis to an entirely scientific process.
Keywords: Biomarker; CB-CAPs; SLE; complement; diagnosis; lupus; monitoring; precision medicine.