GFAP and systemic lupus erythematosus: In double experiments, while no co-staining pattern was observed using patient sera (from both SLE and NPSLE) and the anti-microglial marker antibodies (GFAP or -MBP: Figures 2A–P; both rp < 0.5), NeuN antibody and brain-reactive autoantibodies stain the same cells (Figures 3A–T; rp > 0.5), confirming that brain-reactive autoantibodies labeled neuronal targets.