2
In primary T lymphocytes we show that CD28 ligation leads to the rapid intracellular formation of reactive oxygen intermediates ( ROIs ) which are required for CD28 -mediated activation of the NF-kappa B / CD28 -responsive complex and IL-2 expression .
 CD28, CD28, CD28, primary T lymphocytes, NF-kappa B, CD28 -responsive complex, 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:
 CD28, CD28, CD28, primary T lymphocytes, NF-kappa B, CD28 -responsive complex, IL-2