Serum platelet-activating factor acetylhydrolase (PAF-AH) activity in morethan 3000 healthy Japanese

Background: A spectrophotometric assay for platelet-activating factor acety lhydrolase (PAF-AH) activity differs from the radioisotopic assay in its va lue because of a difference in substrate specificity. The spectrophotometri c assay is more precise than the radioisotopic assay, providing information that is not clear with the radioisotopic assay, Methods: We measured the s erum PAF-All activity in 3106 healthy Japanese, utilizing the spectrophotom etric assay with an Hitachi 7170 automatic analyzer. We also measured the s erum PAF-AH activity in 18 healthy volunteers to investigate the effect of diet and the change in activity in a day and over 6 weeks. Changes were exa mined at 0 (day 1), 1, 2, 4 and 6 weeks. Results: The mean value for female s was significantly lower than that of males at the 5% level and both male and female activity had a tendency to increase with advancing age. It is kn own that the PAF-AH is primarily associated with LDL in blood and the PAF-A ll activity correlated with the total cholesterol (r = 0.52, n = 126) and t he LDL cholesterol (r = 0.60, n = 126) concentrations. In the diet study, t here was no observable effect on activity. No difference in PAF-AH activity was observed between serum and plasma sample types. The serum PAF-AH activ ity was stable at 7 degreesC for at least 7 days and at -20 degreesC for at least 2 months. Conclusions: The serum PAF-AH activity in women was lower than in men until the menopausal age was reached. We could use not only fre sh fasting serum, but also plasma sample, non-fasting sample and stored sam ple to estimate the PAF-AH activity. (C) 2001 Elsevier Science B.V. All rig hts reserved.