Measurement of complement components in systemic lupus erythematosus by radial immunodiffusion

Total hemolytic complement activity (CH50) and levels of C4, C5, and Factor B determined by commercially available radial immunodiffusion plates were compared in sera from patients with systemic lupus erythematosus. There was a significant correlation between CH50, C4 and C5, but no correlation between Factor B and any of the other indices of complement activity measured.