23814
Monocyte - derived DCs and THP - 1 cells were exposed to ( a ) haptens with cysteine , lysine , or cysteine / lysine reactivity , ( b ) pro - / prehaptens , and ( c ) nonsensitizing molecules with reducing or oxidative properties ( 17 molecules in total ) .
 cysteine, lysine, cysteine, lysine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 cysteine, lysine, cysteine, lysine