PGF2-isoprostanes formed during copper-induced oxidation of low-density lipoproteins are the prostaglandins that cross-react with PGE2 antibodies.
It has been previously shown that LDL oxidation can produce a prostaglandin artifact(s) which cross-reacts with PGE2 antibodies. The nature of this cross-reacting material had not been identified. In this study we have examined the products of LDL oxidation and found substances cross-reacting with both PGE2 and LTB4 antibodies. Lipid extracts of copper oxidised LDL were separated by reverse-phase HPLC and fractions cross-reacting with PGE2 antibody identified. Fractions were collected and examined by GC-MS as methyl ester TMS ether derivatives. 8-epi PGF2 alpha (8-isoprostane) was identified as one of the major metabolites eluting in fractions cross-reacting with PGE2. 8-epi-PGF2 alpha showed 4% cross-reactivity with a PGE2 antibody but very little with LTB4 or thromboxane B2 antibodies. Treatment of oxidised LDL with a specific 8-isoprostane antibody removed any detectable PGE2 levels in subsequent PGE2 RIA. The generation of cross-reacting material during LDL oxidation was not influenced by indomethacin. The generation of 8-isoprostanes by free radical oxidation of arachidonic acid in LDL may explain much of the cross-reactivity seen with PGE2 antibodies. The identity of substances cross-reacting with LTB4 have yet to be identified.
Proudfoot
J M
JM
Department of Medicine, University of Western Australia, Perth.
Beilin
L J
LJ
Croft
K D
KD
D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000494:pharmacology*; D003429:Cross Reactions; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000032:analysis* / Q000276:immunology; D015232:Dinoprostone / Q000032:analysis* / Q000276:immunology; D004912:Erythrocytes / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007975:Leukotriene B4 / Q000032:analysis / Q000276:immunology; D008077:Lipoproteins, LDL / Q000097:blood* / Q000737:chemistry / Q000187:drug effects; D010084:Oxidation-Reduction; D011863:Radioimmunoassay
D008077:Lipoproteins, LDL; D007975:Leukotriene B4; C075750:8-epi-prostaglandin F2alpha; D003300:Copper; D015237:Dinoprost; D015232:Dinoprostone