INTERACTION OF MONOCLONAL-ANTIBODY AGAINST P-SELECTIN WITH ACTIVATED PLATELETS AND ENDOTHELIAL-CELLS - HETEROGENEITY OF P-SELECTIN EXPRESSION IN ENDOTHELIAL-CELLS FROM HUMAN AORTA

Monoclonal antibody (mAb) CRC81 against P-selectin, a membrane cell ad hesion protein of platelets and endothelial cells (EC), has been devel oped and characterized. The antibody selectively interacts with the su rface of activated platelets and EC due to the redistribution of P-sel ectin from intracellular granules to the cell surface. CRC81 recognize s not only human but also canine and rabbit P-selectin; Using antibody CRC81 it was shown that EC from human aorta are heterogeneous in rega rd to P-selectin content. Some cells in culture contained no P-selecti n, although they were positively stained for von Willebrand factor, a marker of EC, that is co-localized with P-selectin in Weibel-Palade bo dies. The percentage of P-selectin-negative cells strongly increased d uring the course of cell passaging. In primary culture of aortic EC th e content of such cells was about 15%, but after the 6th passage it ex ceeded 90%.