PGF(2)-ISOPROSTANES FORMED DURING COPPER-INDUCED OXIDATION OF LOW-DENSITY LIPOPROTEINS ARE THE PROSTAGLANDINS THAT CROSS-REACT WITH PGE(2) ANTIBODIES

It has been previously shown that LDL oxidation can produce a prostagl andin artifact(s) which cross-reacts with PGE(2) antibodies. The natur e of this cross-reacting material had not been identified. In this stu dy we have examined the products of LDL oxidation and found substances cross-reacting with both PGE(2) and LTB(4) antibodies. Lipid extracts of copper oxidised LDL were separated by reverse-phase HPLC and fract ions cross-reacting with PGE(2) antibody identified. Fractions were co llected and examined by GC-MS as methyl ester TMS ether derivatives. 8 -epi PGF(2 alpha) (8-isoprostane) was identified as one of the major m etabolites eluting in fractions cross-reacting with PGE(2). 8-epi-PGF( 2 alpha) showed 4% cross-reactivity with a PGE(2) antibody but very li ttle with LTB(4) or thromboxane Bz antibodies. Treatment of oxidised L DL with a specific 8-isoprostane antibody removed any detectable PGE(2 ) levels in subsequent PGE(2) RIA. The generation of cross-reacting ma terial during LDL oxidation was not influenced by indomethacin. The ge neration of 8-isoprostanes by free radical oxidation of arachidonic ac id in LDL may explain much of the cross-reactivity seen with PGE(2) an tibodies. The identity of substances cross-reacting with LTB(4) have y et to be identified. (C) 1995 Academic Press, Inc.