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We next tested directly whether NK cell killing was active in our system using both short - term ( 4 - h ) chromium release assays ( data not shown ) and a flow cytometric assay which allowed us to follow the survival of the autologous iDCs in the presence of NK cells over longer periods ( Fig . 3 ) .
 NK cell, iDCs, NK cells
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 NK cell, iDCs, NK cells