12877
Cytokines , IL-2 , IL-4 , IL-6 , IL-7 , IL-12 , and IL-15 are key regulators of human peripheral blood T and NK cell activation and differentiation but the precise mechanisms that give rise to their differential activities within these cells are not clear.
 Cytokines, IL-4, IL-12, IL-7, IL-15, IL-6, IL-2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 Cytokines, IL-4, IL-12, IL-7, IL-15, IL-6, IL-2