Macrophages are innate myeloid cells involved in health and disease. They can be phenotyped with four independent but complementary approaches: expression of cell surface antigens, expression of transcription factors, production of cytokines, and production of specific enzymes related to function. In humans, CD antigens include CD14, CD312, CD115, and CD16. Subset-specific markers include CD163 and CD204, both scavenger receptors expressed by M2 macrophages, CD301, and CD206. Macrophages can be identified using flow cytometry or immunohistochemical staining by their specific expression of proteins such as CD14, CD40, CD11b, CD64, F4/80 (mice)/EMR1(human), lysozyme M, MAC-1/MAC-3 and CD68.
Macrophages inhibits tumor growth and reduces cancer mortality. In human cancers, macrophages are identified by immunohistochemical staining with antibodies against CD68. CD163 is used as a marker for TAMs, as it is abundant, sensitive and accurate.