Complex-release activity (CRA) of complement was measured in 50 systemic lupus erythematosus (SLE) patients by a simplified method using peroxidase as an antigen in the immune complex. The relation between CRA and other complement levels was investigated, and the influence of CRA on the pathogenesis of SLE was discussed.CRA and ACRA (CRA via the alternative pathway) in SLE were lower than those in normal subjects. CRA and ACRA in SLE correlated well with CH50, ACH50, C3, C4 and factor B. The enhancement of CRA via the classical pathway in SLE was less strong than that in normal subjects. As reduced CRA normalized shortly after the administration of corticosteroid in some SLE patients with persistent hypocomplementemia, the measurement of CRA might be more useful than that of CH50 for clinical purposes. The above results suggest that the alternative complement pathway was activated by immune complexes in vivo and that CRA might play an important role in the clearance of immune complexes in vivo.
alternative complement pathway