Renal M2-like macrophages in LN patients selectively express CD163 (haptoglobin–hemoglobin complex scavenger) and SLC40A1, tied to iron homeostasis (219, 220): 1) SLE-associated autoimmune hemolysis and glomerular injury-induced erythrocyte lysis generate excess haptoglobin–hemoglobin complexes. The gene discussed is HP; the disease is systemic lupus erythematosus.