Hemosiderin-laden macrophages are basically a white blood cell infused with a large amount of an iron-storing compound called hemosiderin. Iron is a toxic metal that is found in the blood and in a number of organs such as the spleen, liver and also in bone marrow. Hemosiderin-laden macrophages are most likely to be found in the blood around a blood hemorrhage.
Macrophages or white blood cells, as they are more commonly known, are one of the body’s primary defense mechanisms. They are eukaryotic cells that either provide general defense or specific targeted defense. This is akin to the distinction between a police patrol and a special investigation into a crime. In non-specific defense encounters, the white blood cell identifies a foreign element, usually a pathogen, and eats it. In a targeted attack, specific types of white blood cells are summoned by chemical compounds to deal with a specific target such as a pathogen.
The pathogens are eaten via the process of phagocytosis and are caught in the white blood cell’s phagosome. Enzymes then break the pathogen down into its constituent parts. The enzymes, however, will eventually kill the white blood cell itself.
Hemosiderin, as found in hemosiderin-laden macrophages, is one of many compounds used by the human body to store iron. The molecule compound is never found free in the body’s circulatory system, but is always found within cells. It is most commonly found in white blood cells and cells that are used to store iron.
All hemosiderin-laden macrophages create hemosiderin using hemoglobin in the blood. It first eats the hemoglobin via phagocytosis and then breaks it down. The degradation process creates hemosiderin and also porphyrin as a byproduct. The hemosiderin is then used, by an enzyme, to bind the iron to make it safe within the white blood cell.
Hemorrhages occur when a rent in a tissue within the body allows blood to leak out. Bleeding can be dangerous to the body and, in severe cases, can lead to a drop in blood pressure and, ultimately, death. Such hemorrhages can occur both internally and externally. Naturally, internal hemorrhages are harder to spot, as the blood leaks within the body.
Holes and rents in tissues that cause bleeding are repaired, if possible, by platelets in the blood. The role of hemosiderin-laden macrophages appears to be either to store iron that may leak out of the tissue or to protect the body from the effects of loose toxic iron in the blood. This appears to be a secondary protective function of the white blood cell.