Human and rabbit platelets form platelet-activating factor in response to calcium ionophore.

Homogenous preparations of human and rabbit platelets synthesized platelet-activating factor (PAF) when stimulated by calcium ionophore A23187. PAF was isolated by high performance liquid chromatography (HPLC) on a Lichrosorb Si60 column. PAF was well separated from other phospholipids especially sphingomyelin and lysolecithin. The retention times of PAF derived from human or rabbit platelets were identical to the commercially available semisynthetic PAF and radiolabeled PAF. The amount of PAF was determined by the extent to which it induced the aggregation of washed rabbit platelets.