1730
Co-stimulation of T-lymphocytes by T-cell receptor ( TcR ) occupancy and activation of the CD28 surface molecule results in enhanced proliferation and interleukin 2 ( IL-2 ) production .
 T-lymphocytes, interleukin 2, T-cell receptor, IL-2, TcR, CD28 surface molecule, CD28
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:
 T-lymphocytes, interleukin 2, T-cell receptor, IL-2, TcR, CD28 surface molecule, CD28