13417
Initial signaling through the CD4 receptor played a major role in the sensitization of HIV-infected T cells to undergo apoptosis .
 HIV-infected T cells, CD4 receptor, CD4
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:
 HIV-infected T cells, CD4 receptor, CD4