Tissue Macrophages
A majority of macrophages are stationed at strategic points where microbial invasion or accumulation of dust is likely to occur. Each type of macrophage, determined by its location, has a specific name:
| Name of cell | Location |
| Dust cells/Alveolar macrophages | pulmonary alveolus of lungs |
| Histiocytes | connective tissue |
| Kupffer cells | liver |
| Microglia | neural tissue |
| Epithelioid cells | granulomas |
| Osteoclasts | bone |
| Sinusoidal lining cells | spleen |
| Giant cells | Connective Tissue |
| Peritoneal macrophages | Peritoneal cavity |
Investigations concerning Kupffer cells are hampered because in humans, Kupffer cells are only accessible for immunohistochemical analysis from biopsies or autopsies. From rats and mice, they are difficult to isolate, and after purification, only approximately 5 million cells can be obtained from one mouse.
Macrophages can express paracrine functions within organs that are specific to the function of that organ. In the testis for example, macrophages have been shown to be able to interact with Leydig cells by secreting 25-hydroxycholesterol, an oxysterol that can be converted to testosterone by neighbouring Leydig cells. Also, testicular macrophages may participate in creating an immune privileged environment in the testis, and in mediating infertility during inflammation of the testis.
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