Secreted, extracellular space . Associates with both LDL and HDL particles in plasma (PubMed:11590221, PubMed:12821559, PubMed:18434304, PubMed:10066756). Mainly associates with pro-inflammatory electronegative LDL particles (PubMed:12821559). .
Plasma (PubMed:11590221, PubMed:12821559). Secreted by macrophages (at protein level) (PubMed:11590221).