Quantitation by Radioimmunoassay of PAF in Human Saliva

Abstract

Approximately 75% of the PAF present in saliva is recovered on extraction of whole saliva (0.8 vol) with chloroform/methanol/water {2:2:1, v/v/v}. PAF levels, dete~ mined by our recently developed radioimmunoassay, in saliva extracts ranged from 0.5-21 nghnL with 59% between 2-6 ng/mL. These figures, for apparently healthy subjects, are higher than previously reported levels obtained by platelet assays. The validity of our radioimmunoassay results was checked by isolating and quantitating the PAF fraction from whole saliva. In addition, when we ex~mined our saliva samples by platelet aggregation, low levels of PAF, comparable with the values found in the literature, were detected. Investigations revealed the presence of a substance(s) which inhibited PAFinduced platelet aggregation but which did not affect the radioimmunoassay.

PAF levels in saliva are regulated by inflammatory cells

“…This finding suggests that at least a fraction of salivary PAF is associated with cells present in whole, mixed saliva, and should be taken into account when studies are planned to compare salivary PAF levels between subjects with different pathological conditions. It has been reported previously that salivary PAF follows a circadian variation, with peak levels in the morning (17). It is conceivable that the changes observed are related to an influx of inflammatory cells, most probably leucocytes, in saliva as a function of time after oral hygiene.…”

“…The recovered PAF was then resuspended in 1 ml of assay buffer containing sodium azide 0. I%, Tween 0.05%, Na citrate 50 mM; the samples were centrifuged at 12,OOOg for 10 min to remove any debris and then assayed by radioimmunoassay (RIA) (NEN-Du Pont, Boston MA, USA), as described (14,16,17). The cross-reactivity of the antibody used with lyso-PAF, the product of PAFdegradation by acetylhydrolase, was lower than 0.003%, thus excluding any interference from PAF degradation products in the assay (17).…”

“…I%, Tween 0.05%, Na citrate 50 mM; the samples were centrifuged at 12,OOOg for 10 min to remove any debris and then assayed by radioimmunoassay (RIA) (NEN-Du Pont, Boston MA, USA), as described (14,16,17). The cross-reactivity of the antibody used with lyso-PAF, the product of PAFdegradation by acetylhydrolase, was lower than 0.003%, thus excluding any interference from PAF degradation products in the assay (17). In addition cross-reactivities with phosphatidylcholine and sphingomyelin, the most abundant lipids in saliva, were extremely low, so that even supraphysiologic concentrations of these lipids (220 ,ug/ml) did not interfere with the assay (18,19).…”

PAF and the Digestive Tract. A Review

“…This atraumatic approach reduces artefactual mediator formation and is a good index of the balance between production and degradation in-vivo. PAF can be easily recovered from human saliva (Cooney et al 1991), gastric juice (Sobhani et a1 1993) or blood (Caramel0 et al 1987.…”

Βιοσύνθεση και αποικοδόμηση του παράγοντα ενεργοποίησης των αιμοπεταλίων (paf) σε ασθενείς με ιδιοπαθή σπειραματονεφρίτιδα

“…Στην συνέχεια βρέθηκε ότι τα κύτταρα των περισσοτέρων ιστών έχουν την ικανότητα να συνθέτουν PAF σε φυσιολογικές αλλά και παθολογικές καταστάσεις. Φυσική συνέπεια της δυνατότητας των κυττάρων να εκκρίνουν τον PAF που συνθέτουν ήταν η ανίχνευσή του σε πολλά βιολογικά υγρά όπως πλάσμα 22 , ούρα 23 , σίελος 24 , γαστρικό υγρό 25 , και αμνιακό υγρό 26 . Τα τελευταία χρόνια η ύπαρξη του PAF έχει βρεθεί σε φυτικά κύτταρα, σε κατώτερους ζωικούς οργανισμούς και σε μονοκύτταρους ευκαρυωτικούς οργανισμούς.…”