Platelet-Activating Factor in Human Normal Tears

Abstract

To our knowledge, this is the first report of the concentrations of different species of PAF (C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF) in human tears.

Pharmacokinetic Analysis of Platelet-Activating Factor in the Tears of Guinea Pigs with Allergic Conjunctivitis

“…We were previously able to detect C18:0-PAF in human tears using LC/MS/MS. 11 Ramesha and Pickett have suggested that cells generate unique patterns of PAF specificity depending on the availability of precursor substrates. 12 Therefore, this discrepancy in the ability to detect C18:0-PAF may reflect species-related differences in guinea pigs and humans.…”

“…15 We also demonstrated that there was a trend toward higher amounts of PAF in human tears of AC patients using LC/MS/MS. 11 Based on these results, we were interested in characterizing in more detail the levels of each species of PAF in AC, using a guinea pig model of AC development. In this study, we found that the mean concentrations of C16:0-PAF, C16:0-lyso-PAF, and C18:0-lyso-PAF in animals that had been actively sensitized to ovalbumin increased up to 6 h postchallenge, and that there was no corresponding increase in unsensitized animals (Figs.…”

“…We found a significant correlation between the concentration of C18:0-PAF and C16:0-PAF, and the concentrations of C18:0-lyso-PAF and C16:0-lyso-PAF. 11 Although cellular sources of PAF in tears remain unclear, infiltrating inflammatory cells into the conjunctiva could be considered to be the PAF-producing cells because more inflammatory cells, such as eosinophils, infiltrate into the conjunctiva and the tears as the severity of AC increases. 15 We also demonstrated that there was a trend toward higher amounts of PAF in human tears of AC patients using LC/MS/MS.…”

“…This result is in good agreement with our previous results from analysis of PAF in human tears. 11 It seems that as production of PAF increases with the progression of AC, PAF AH degrades PAF into lyso-PAF, thus maintaining the balance between PAF and lyso-PAF. We also found a significant correlation between C16:0-lyso-PAF and C18:0-lyso-PAF in both sensitized and unsensitized animals, suggesting that the proportion of each species of PAF is affected by the specific precursor substrates available in PAF-producing cells.…”

“…10 We also reported that in patients with allergic conjunctivitis (AC), there is a trend toward higher levels of PAF in tears, compared to healthy control individuals. 11 In this study, we examined the levels of C18:0-PAF, C18:0-lyso-PAF, C16:0-PAF, and C16:0-lyso-PAF in tear samples from guinea pigs with AC using liquid chromatography-tandem mass spectrometry (LC/MS/MS).…”