12246
BACKGROUND: Inhibition of complement in small animal models of xenotransplantation has demonstrated graft infiltration with natural killer (NK) cells and monocytes associated with endothelial cell ( EC ) activation .
 ( cell type: natural killer (NK) cells, None) , ( cell type: endothelial cell, None) , ( cell type: EC, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( cell type: natural killer (NK) cells, None) , ( cell type: endothelial cell, None) , ( cell type: EC, None) 