Microdetermination of prostaglandin E 2 in joint fluid in rheumatoid arthritis patients using gas chromatography/selected ion monitoring

Abstract

We devised an effective purification for the microdetermination of prostaglandin E 2 (PGE 2) in human joint fluid using gas chromatography/selected ion monitoring and determined PGE 2 in the joint fluid in rheumatoid arthritis (RA) patients using this method. The methyl ester- methoxime- tert-butyldimethylsilyl ether derivative was prepared, then gas chromatography/selected ion monitoring was carried out by monitoring the ion at m/z 566.4 for PGE 2 and at m/z 570.4 for the internal standard (PGE 2- d 4). A good linear response over the range of 10 pg to 50 ng was demonstrated. We detected PGE 2 to a level of about 46 pg/ml in the joint fluid of RA patients. The level of PGE 2 in RA patients was significantly higher than that in osteoarthritis patients used as controls. Moreover, we measured inflammatory cytokine (IL-1β, TNFα, IL-6 receptor) levels in joint fluid by using enzyme-linked immunosorbent assay. A relationships between the PGE 2 level in joint fluid and these cytokines or biochemical data as the indicator of RA disease was not observed. We found that the PGE 2 level in each patient was influenced by therapeutic drugs. The PGE 2 level in RA patients with non-steroidal anti-inflammatory drugs was lower than with steroids.