C5 and systemic lupus erythematosus: In an observational study of 23 patients with SLE that aimed to observe the fluctuation of C3a and C5a in relation to SLE disease flares, in addition to the elevation of serum of C3a and C5a that was more prominent in patients with acute CNS dysfunction compared with patients with active SLE without CNS involvement, postmortem examination of 2 patients revealed neutrophil infiltration that occluded cerebral vessels (160).