Oxidized low-density lipoprotein (oxLDL) particles contain low molecular weight species which promote the differentiation of monocytes and activate PMNL. Many of these substances were recently isolated and purified from oxLDL, and identified as phosphatidylcholine species containing a fragmented, oxidized short-chain fatty acid remnant at the sn-2 position. One of these substances isolated from oxLDL and identified as azelaoyl PAF is a potent PPARγ agonist. 1-Palmitoyl-2-glutaryl phosphatidylcholine (PGPC) and 1-(palmitoyl)-2-(5-oxovaleroyl) phosphatidylcholine (POV-PC) are closely related compounds with strikingly different activity. PGPC treatment of vascular endothelial cells induces the expression of both E-selectin and VCAM-1, and increases endothelial cell binding by both neutrophils and monocytes. This contrasts with POV-PC treatment, which stimulates only monocyte binding, and strongly inhibits the LPS-induced binding of neutrophils.