22971
Interestingly , the SE - containing HLA - DRB1 molecules display a pocket with a high affinity for citrullinated antigens , which are found at higher levels in subjects prone to develop RA .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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