The Fourth Component of Complement in the Cerebrospinal Fluid in Systemic Lupus Erythematosus

Abstract

Of 35 patients with systemic lupus erythematosus (SLE) studied for up to 18 months, 6 had acute neurologic disease and 3 had acute psychiatric syndromes attributed to SLE during which the mean hemolytic titer of the fourth component of complement in the cerebrospinal fluid (CSF C4) did not differ significantly from the mean of 50 titers in control SLE patients. However, in 4 patients serial determinations disclosed a depression of titer at the time of acute central nervous system involvement (P < 0.01). Hemolytic C4 was unstable in CSF stored at ‐45°C. Two decay patterns were noted in SLE patients; titers fell more rapidly in patients with more active lupus (P < 0.001). The findings support the postulate that immune injury underlies the neurologic manifestations of SLE. Copyright © 1973 American College of Rheumatology