8431
The immunoglobulin heavy chain ( IgH ) class switch recombination of B lymphocytes preferentially targets unrearranged IgH genes that have already been rendered transcriptionally active .
 ( protein: IgH, None) , ( cell type: B lymphocytes, None) , ( protein: immunoglobulin heavy chain, None) , ( DNA: IgH genes, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( protein: IgH, None) , ( cell type: B lymphocytes, None) , ( protein: immunoglobulin heavy chain, None) , ( DNA: IgH genes, None) 