6262
Although the TNF-alpha level in culture supernatants was below the sensitivity of an ELISA assay system , addition of anti- TNF-alpha antibody in culture medium could partially suppress the heat shock induced HIV-1 production .
 TNF-alpha, TNF-alpha
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:
 TNF-alpha, TNF-alpha