HRG and monocytic leukemia: HRG was shown to facilitate necrotic cell clearance by phagocytes through preferential binding to HS on THP-1 cells (a human macrophage-like monocytic leukemia cell line) [98], as supported by the cleavage of HS leading to reduced binding of HRGP (co-purified IgG with HRG) to THP-1 cells.