Macrophages are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris, and foreign substances, which do not have proteins that are specific to healthy body cells on their surface. This process is called phagocytosis, which acts to defend the host against infection and injury.
Gram stain of a macrophage with ingested S. epidermidis bacteria, seen as purple granules within its cytoplasm.
A macrophage stretching its "arms" (filopodia) to engulf two particles, possibly pathogens, in a mouse (trypan blue exclusion staining).
Siderophage
Anthracotic macrophage
White blood cells, also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. White blood cells include three main subtypes: granulocytes, lymphocytes and monocytes.
A scanning electron microscope image of normal circulating human blood. In addition to the irregularly shaped leukocytes, both red blood cells and many small disc-shaped platelets are visible.
Neutrophil engulfing anthrax bacteria