C4A and lupus nephritis: ✔ Kidney damage – proteinuria >0.5 g/day or cellular casts– lupus nephritis - divided into 5 classes (assessment requires biopsy)✔ Hematological impairment – mild leukopenia: 3,000 – 4,000/mm3  – lymphopenia: <1500 cells/mm3  – anemia  – mild/profound thrombocytopenia <150,000 - 10,000  – antiphospholipid antibodies✔ Immunological disorders – ANA – high sensitivity  – anti-dsDNA – high specificity  – anti-Ro (anti-SSA) and anti-La (anti-SSB) antibodies  – anti-SM, anti-RNP, ENA  – hypocomplementemia (C3,C4)  + discordant ESR – CRP