1545
The presence of a flagellum was not required for binding of P. aeruginosa to macrophages but was critical for the subsequent internalization of the bacterium , suggesting that this factor or a surface ligand associated with its assembly was responsible for stimulation of nonopsonic phagocytosis .
 cell type: macrophages
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 cell type: macrophages