4553
In the current studies, IL-2 production by T cells from elderly (mean 78 years) and young (mean 37 years) humans was measured in cultures stimulated with PHA , PHA plus PMA , crosslinked anti-CD3 mAB OKT3 plus PMA , or PMA plus ionomycin .
 ( protein: PHA, None) , ( protein: IL-2, None) , ( cell type: T cells, None) , ( protein: PHA, 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:
 ( protein: PHA, None) , ( protein: IL-2, None) , ( cell type: T cells, None) , ( protein: PHA, None) 