Specific binding of antibodies to platelet-activating factor (PAF) as demonstrated by thin-layer...

The specificity of rabbit antibodies produced by injection of 1-O-(15'-carboxypentadecyl)-2-N,N-dimethylcarbamoyl-sn-glycero-3- phosphocholine bovine serum albumin (BSA) conjugates was examined by a thin-layer chromatography (TLC/immunostaining method. Phosphatidylcholine (PC), lysophosphatidylcholine (lysoPC), lyso platelet-activating factor (lysoPAF), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS), sphingomyelin (SM), phosphatidylinositol (PI), phosphatidic acid (PA) and cardiolipin (CL) were not immunostained. Among several synthetic PAF-related compounds, the antibodies only bound to PAF agonists which have the activity to induce washed rabbit platelet aggregation. The results suggest that the binding sites of the antibodies on the PAF molecule are the acetyl group at the sn-2 position and the choline moiety at the sn-3 position of glycerol, both of which are essential for exerting the biological function of PAF and for binding to the PAF receptors located on cellular membranes.