7217
Although many functions of human alveolar macrophages are altered compared with their precursor cell , the blood monocyte ( monocyte ), the reason(s) for these functional changes have not been determined.
 blood monocyte, human alveolar macrophages, precursor cell, monocyte
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:
 blood monocyte, human alveolar macrophages, precursor cell, monocyte