PS-Liposome and Ox-LDL Bind to Different Sites of the Immunodominant Domain (#155-183) of CD36: A Study with GS95, a New Anti-CD36 Monoclonal Antibody

Abstract

CD36, a multifunctional adhesive receptor on a variety of cells such as monocytes and platelets, has been implicated in clearance of modified LDL and in the removal of apoptotic or senescent cells. We recently developed a new anti-CD36 monoclonal antibody, GS95. We determined the binding site of phosphatidylserine (PS)-1iposome on CD36 by flow cytometric analysis of competitive bindings between phospholipid-liposomes or synthetic CD36 peptides and FITC-1abeled anti-CD36 antibodies (GS95, OKM5, and FA6-152). The epitope of GS95 was mapped to the amino acid sequence #162–183 of CD36 that was partially overlapped with, but distinct from, #155–183, which has been reported as the epitopes of two commercially available antibodies, OKM5 and FA6-152. Oxidized-LDL dose-dependently inhibited bindings of both GS95 and OKM5 antibodies to platelet CD36, while PS-liposome inhibited the binding of GS95 but not OKM5 or FA6-152. These results indicate that the binding site of PS-liposome on platelet CD36 is not identical to that of oxidized-LDL and may be located in the amino acid sequence #162–183.