There is increasing evidence that endogenously generated aldehydes formed a
s a result of lipid peroxidation are involved in the pathophysiological eff
ects associated with oxidative stress in cells and tissues. Malondialdehyde
(MDA), a major product of lipid peroxidation, can modify amines present on
the cell surface and thereby introduce negative charges that can affect th
e interfacial ionic layer. We show that lipid peroxidation of RBC generates
MDA adducts that, similar to phosphatidylserine (PS), bind annexin V in a
Ca2+-dependent manner. Like PS, these adducts also promote the "PS-dependen
t" prothrombinase assays, albeit to lower levels, These results indicate th
at annexin V binding cannot be used as an exclusive indicator of cell surfa
ce PS and raise the possibility that some phenomenon attributed to PS may,
in fact, also involve aldehyde-lipid adducts.