12674
These results suggest that activation of Stat4 , which is necessary for the differentiation of naive T cells into polarized Th1 cells , is not sufficient to induce phenotype reversal of human Th2 cells .
 naive T cells, Th1 cells, Stat4, human Th2 cells
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:
 naive T cells, Th1 cells, Stat4, human Th2 cells