Inflammatory sites as a source of plasma neopterin: measurement of high levels of neopterin and markers of oxidative stress in pus drained from human abscesses.
OBJECTIVE
Plasma neopterin is a clinical marker of inflammation. Interferon-gamma triggers 7,8-dihydroneopterin and its oxidation product, neopterin, to be released from macrophages. 7,8-dihydroneopterin is a potent antioxidant which can protect macrophages from oxidative damage in vitro. This study examined whether 7,8-dihydroneopterin/neopterin levels reach sufficient concentrations in human pus to provide antioxidant activity and be the source of plasma neopterin.


METHODS
Pus was removed by needle aspiration from 19 patients and examined for total neopterin, protein-bound DOPA, dityrosine, alpha-tocopherol, lipid oxidation and protein carbonyls.


RESULTS
Total neopterin was detected between 50 nM and 1.2 microM, with an average concentration of 0.51 microM. Significant quantities of oxidized proteins and lipids were detected. alpha-Tocopherol concentrations positively correlate with total neopterin levels.


CONCLUSIONS
Total neopterin levels found in the pus was up to 100 times higher than that reported in plasma, suggesting plasma neopterin originates from inflammatory sites. The concentration of total neopterin suggests that 7,8-dihydroneopterin could act as an antioxidant during inflammation.
Firth
Carole A
CA
Free Radical Biochemistry Laboratory, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
Laing
Andrew D
AD
Baird
Sarah K
SK
Pearson
Joseph
J
Gieseg
Steven P
SP
D000038:Abscess / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004295:Dihydroxyphenylalanine / Q000032:analysis; D005260:Female; D006801:Humans; D007249:Inflammation / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D019798:Neopterin / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood*; D018384:Oxidative Stress; D013492:Suppuration / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis; D024502:alpha-Tocopherol / Q000032:analysis
C000976:7,8-dihydroneopterin; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D019798:Neopterin; C007543:dityrosine; D024502:alpha-Tocopherol