Measurement of erythrocyte C4d and complement receptor 1 in systemic lupus erythematosus

Abstract

This is the first report of abnormal levels of E-C4d in human disease. We found that abnormally high levels of E-C4d and low levels of E-CR1 are characteristic of SLE, and combined measurement of the 2 molecules has high diagnostic sensitivity and specificity for lupus. Determination of E-C4d/E-CR1 levels may be a useful addition to current tests and criteria for SLE diagnosis.