[Adherent reaction among activated platelets, polymorphonuclear cells and vascular endothelial cells under thrombin stimulation or shear stress].

Platelet activation in addition to blood coagulation abnormality is regarded as a primary factor of thrombosis by atherosclerotic obstruction. Therefore, the platelet activation on atherosclerosis is considered to correlate with shear stress generated between blood cells and endothelial cells in blood flow. P-selectin on the surface of the platelet membrane is measured by flowcytometry as a marker of platelet activation. Herein, we examined the phenomena of platelet activation and adherent platelets with leukocytes (ad-P.L) on stored platelet concentration (PC) and chronic rheumatoid arthritis (RA), moreover, of the adherent platelets or polymorphonuclear cells (PMN) with endothelial cells (EC) in shear stress by using an apparatus we devised. The rate of platelet activation and ad-P.L increased in PC with storage, and the sensitivity of platelets to thrombin decreased. The rate of platelet activation and ad-P.L increased in RA in vivo. Many adherent platelets with EC were found at a low shear rate on normal EC but at a high shear rate on denatured EC without any specific adherent property. Adherent PMN with EC had several hundred times more denatured EC than normal EC and the relationship with shear rate disappeared on denatured EC. The platelet activation and relationship between platelets or leukocytes and EC as to the cause of thrombosis are important subjects for future studies.