A specific, sensitive radioimmunoassay for platelet-activating factor (PAF).

A specific radioimmunoassay (RIA) has been developed for platelet-activating factor (PAF) and shown to be sensitive over the range 10-1000 pg (0.02-2 pmol). The anti-PAF antibodies showed specificity for the acetyl group at the C2 position of the PAF molecule and exhibited no significant cross-reactivity with lyso-PAF or the naturally occurring lipids including lecithin and lysolecithin. The sensitivity of the RIA was at least as good as the platelet-based assays for PAF but the RIA was simpler to perform, had a higher capacity and did not have the drawback of the inherent variability associated with the bioassays.