C3 and systemic lupus erythematosus: In an analysis of differentiating ANA- SLE from OD (Figure 2E), TC4d (AUC: 0.73) significantly outperformed C3 (0.57, p = 0.03), anti-dsDNA (0.46, p = 0.04) and anti-Smith (0.44, p < 0.01).