All of the following promote platelet aggregation except

Factors inhibiting platelet aggregation are ATP, PGI2 or prostacyclin, Aspirin, coisol Factors oring platelet aggregation are Thrombospondin which helps in fixation of platelet, platelet activating factor, ADP, Thromboxane A2, Ca2+,vWF etc. Plasmin also helps in platelet aggregation. Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no.102,103