The present invention provides methods for identifying molecular components (e.g. proteins and/or lipids) that are characteristic of vascular endothelia associated with a particular disease and are not also present in (i) normal (non-disease associated) vascular endothelia or (ii) non-disease associated vascular endothelia subjected to altered conditions that accompany the disease but are not unique to the disease. The methods include isolating plasma membrane fractions from disease-associated vascular endothelial cells, from normal (nondisease-associated) vascular endothelial cells and from nondisease-associated vascular endothelial cells subjected to at least one of the altered conditions; purifying and resolving molecular components from these membrane fractions; comparing the components resolved from each of the foregoing vascular endothelial cell sources and identifying components that are present in disease-associated endothelial cells and absent from the normal or otherwise conditioned endothelial cells. The resulting endothelial cell membrane components that are unique to the disease state can be used for diagnostic and/or therapeutic purposes.