Which type of white blood cell becomes macrophages when matured?

Monocytes are the type of white blood cell that can differentiate into macrophages upon maturation. Once they migrate from the bloodstream into tissues, they undergo a transformation into macrophages, which are crucial for the immune response. Macrophages play a vital role in phagocytosing pathogens and dead cells, as well as in antigen presentation, which is important for activating other immune cells. This transformation highlights the important protective function monocytes provide when they become macrophages in various tissues throughout the body.

Other white blood cells, such as lymphocytes, neutrophils, and eosinophils, have distinct roles in the immune system but do not mature into macrophages, making monocytes the correct choice in this context.