Macrophage

White blood cells, or leukocytes, include a specialized type of cell called a macrophage. They are produced as monocytes by stem cells in the bone marrow and they differentiate into either wandering macrophages, which circulate in the bloodstream, or fixed macrophages. Both types of macrophages engulf (phagocytosis) and destroy dead or damaged blood cells and foreign invaders in the body, such as bacteria, protozoa and tumor cells. Fixed macrophages are found in especially vulnerable intracellular areas of the body, such as the lungs, intestines, and liver. When macrophages encounter and destroy foreign invaders they produce fragments and cytokines which activate the acquired immune system.http://www.merck.com/mmpe/sec13/ch163/ch163a.html http://www.mansfield.ohio-state.edu/~sabedon/black16.htm http://courses.washington.edu/conj/bloodcells/phagocytosis.htm

There are two general types of macrophages, normal and inflammatory. Inflammatory macrophages occur in various types of exudates and have specific activities such as peroxidase capabilities. Normal macrophages, which have a life span of 6-16 days, are found in various tissues and have specific names:

1. Lungs - alveolar macrophages
2. Spleen - free and fixed macrophages
3. Liver - Kupffer's cells
4. Skin - histocytes, Langerhan's cell
5. Bone marrow - fixed macrophages
6. Serous fluids - pleural and peritoneal macrophages
7. Connective tissue - histiocytes
8. Lymph nodes - free and fixed macrophages http://nic.sav.sk/logos/books/scientific/node21.html

The content in this page is not a substitute for professional medical advice. If you need information about macrophages, please consult your doctor.