[Demonstration of circulating immune complexes using a C1q-solid phase enzyme immunoassay]

An enzyme-immunoassay for the quantitative determination of circulating immune complexes in human serum is described. The technique uses alkaline phosphatase-conjugated anti-human IgG to detect immune complexes bound to solid phase C1q. This assay is sensitive detecting 4 ng/ml to 60 micrograms/ml aggregated IgG. First data from normal individuals and patients with systemic lupus erythematosus show that this method is specific and sensitive for detection of circulating immune complexes.