8507
The observation that beta 2m with covalently attached peptide can effectively create CTL target structures in vitro offers new possibilities for the in vivo induction of epitope - specific CTL responses by either DNA immunization or injection of the purified epitope - linked beta 2m .
 beta 2m, beta 2m
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 beta 2m, beta 2m