1933
The activity of the immunoglobulin heavy-chain (IgH) enhancer is restricted to B cells , although it binds both B-cell-restricted and ubiquitous transcription factors .
 B cells, immunoglobulin heavy-chain (IgH) enhancer
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:
 B cells, immunoglobulin heavy-chain (IgH) enhancer