Clinical significance of measurement of complement fragments in connective tissue discases

Abstract

Complement fragments, C4d, iC3b and Bb are generated through activation of the complement pathway. The plasma levels of the fragments were measured by means of enzymeimmunoassay to study the clinical significance of them in some connective tissue diseases.
The plasma levels of C4d and iC3b were significantly elevated in patients with SLE, MCTD and RA. The levels of Bb was significantly elevated in plasma from SLE and RA. In SLE, total complement hemolytic activity, CH50, and these fragments levels did not correlate. It is supposed that there are many factors which influence the complement activity in patients with hypocomplementemia, such as the existence of inhibitors or inactivators, reduced synthetic rates and increased rates. The measurement of complement fragments in serial plasma samples obtained from patients with connective tissue diseases, especially with SLE, seemed to be simple and useful to evaluate the activation of complement in vivo.